Common sense tells us that Brood X Periodical Cicada emergence begins in the southern part of the population zone, where the ground temperatures reach 64° first, then progresses to the north as the weather warms. In the forested hills where the lower Piedmont falls away onto the flat landscape of the Atlantic Coastal Plain in Maryland’s Cecil and Harford Counties, the hum of seventeen-year-old insects saturates a listener’s ears from all directions—the climax nears.
Periodical Cicadas, mostly Magicicada septendecim, are well into their breeding cycle along the Piedmont-Atlantic Coastal Plain border right now. Love is in the air.
With all that food flying around, you just knew something unusual was going to show up to eat it. It’s a buffet. It’s a smorgasbord. It’s free, it’s all-you-can-eat, and it seems, at least for the moment, like it’s going to last forever. You know it’ll draw a crowd.
The Mississippi Kite (Ictiniamississippiensis), a trim long-winged bird of prey, is a Neotropical migrant, an insect-eating friend of the farmer, and, as the name “kite” suggests, a buoyant flier. It experiences no winter—breeding in the southern United States from April to July, then heading to South America for the remainder of the year. Its diet consists mostly of large flying insects including beetles, leafhoppers, grasshoppers, dragonflies, and, you guessed it, cicadas. Mississippi Kites frequently hunt in groups—usually catching and devouring their food while on the wing. Pairs nest in woodlands, swamps, and in urban areas with ample prey. They are well known for harmlessly swooping at people who happen to get too close to their nest.
Mississippi Kites nest regularly as far north as southernmost Virginia. For at least three decades now, non-breeding second-year birds known as immatures have been noted as wanderers in the Mid-Atlantic States, particularly in late May and early June. They are seen annually at Cape May, New Jersey. They are rare, but usually seen at least once every year, along the Piedmont-Atlantic Coastal Plain border in northern Delaware, northeastern Maryland, and/or southeastern Pennsylvania. Then came the Brood X Periodical Cicadas of 2021.
During the last week of May and these first days of June, there have been dozens of sightings of cicada-eating Mississippi Kites in locations along the lower Piedmont slope in Harford and Cecil Counties in Maryland, at “Bucktoe Creek Preserve” in southern Chester County, Pennsylvania, and in and near Newark in New Castle County, Delaware. They are being seen daily right on the lower Susquehanna watershed’s doorstep.
Today, we journeyed just south of Mason’s and Dixon’s Delaware-Maryland-Pennsylvania triangle to White Clay Creek State Park along Route 896 north of Newark, Delaware. Once there, we took a short bicycle ride into a wooded neighborhood across the street in Maryland to search for the Mississippi Kites that have been reported there in recent days.
Periodical Cicadas filled the treetops and the airspace just above them.It wasn’t long before Mississippi Kites appeared over the trees along a hilltop clearing to snatch up cicadas for a morning meal.This kite glides on autopilot as it holds a captured cicada in its talons and tears it apart with its hook-shaped bill.At least ten Mississippi Kites have been seen simultaneously at this site or in nearby Newark during recent days. This morning, we saw six.All the Mississippi Kites we saw today were second-year birds. The banded tail is characteristic of both hatch-year (juvenile) and second-year (immature) Mississippi Kites. Of course, at this time of year, hatch-year birds are still in the nest and not flying around pigging out on Periodical Cicadas.The banded tail, gray underside, and white head of a second-year Mississippi Kite. Though known as immature or subadult birds during their second year, there are records of Mississippi Kites successfully breeding at this age. Recent wanderings into the Mid-Atlantic States and New England have led to a spotty expansion of the nesting range there.Mississippi Kites in their second year undergo molt of their flight feathers. The timing can vary greatly among individual birds with diet among the factors affecting the process. This bird is just beginning the replacement of its juvenile remiges and rectrices.Tail molt beginning on this second-year Mississippi Kite. These banded juvenile tail feathers will be replaced by a set of all-dark adult rectrices.A second-year Mississippi Kite with an all-dark adult tail feather (rectrix). An abundance of protein-rich cicadas should provide ample nutrition to keep the molt process going for this maturing bird, at least for another couple of weeks. Relocating inland on the Piedmont could keep this and other kites well-nourished for even longer.
Will groups of Mississippi Kites develop a taste for our seventeen-year cicadas and move north into the Lower Susquehanna River Watershed? Ah, to be young and a nomad—that’s the life. Wandering on a whim with one goal in mind—food. It could very well be that now’s the time to be on the lookout for Mississippi Kites, especially where Brood X Periodical Cicadas are abundant.
The emergence of Brood X Periodical Cicadas is now in full swing. If you visit a forested area, you may hear the distant drone of very large concentrations of one or more of the three species that make up the Brood X event. The increasing volume of a chorus tends to attract exponentially greater numbers of male cicadas from within an expanding radius, causing a swarm to grow larger and louder—attracting more and more females to the breeding site.
Holes in the ground where emerging Brood X Periodical Cicadas have come to the surface.The exuvia of Periodical Cicadas that, following emergence from the soil, have ascended the trunk of an Eastern White Pine. The exuvia is the exoskeletal remains of the cicada’s final molt from a nymph into a flying adult.
Each Periodical Cicada species has a distinctive song. This song concentrates males of the same species at breeding sites—then draws in an abundance of females of the same species to complete the mating process. Large gatherings of Periodical Cicadas can include all three species, but a close look at swarms on State Game Lands 145 in Lebanon County and State Game Lands 46 (Middle Creek Wildlife Management Area) in Lancaster County during recent days found marked separation by two of the three. Most swarms were dominated by Magicicada septendecim, the largest, most widespread, and most common species. However, nearly mono-specific swarms of M. cassinii, the second most numerous species, were found as well. An exceptionally large one was northwest of the village of Colebrook on State Game Lands 145. It was isolated by a tenth of a mile or more from numerous large gatherings of M. septendecim cicadas in the vicinity. These M. cassinii cicadas, with a chorus so loud that it outdistanced the songs made by the nearby swarms of M. septendecim, seized the opportunity to separate both audibly and physically from the more dominant species, thus providing better likelihood of maximizing their breeding success.
Some of the tens of thousands of M. cassinii Periodical Cicadas in a concentration on State Game Lands 145 northwest of Colebrook in Lebanon County, Pennsylvania. This swarm occupied deciduous and evergreen trees on several acres of a south-facing hillside. To provide protection from predators and assure the chance of finding a mate “in the crowd”, lesser numbers of this and the rarer species, Magicicada septendecula, would need to merge into the swarms of the abundant M. septendecim Periodical Cicadas to breed.
The process of identifying Periodical Cicadas is best begun by listening to their choruses, songs, and calls. After all, the sounds of cicadas will lead one to the locations where they are most abundant. The two most common species, M. septendecim and M. cassinii, produce a buzzy chorus that, when consisting of hundreds or thousands of cicadas “singing” in unison, creates a droning wail that can carry for a quarter of a mile or more. It’s a surreal humming sound that may remind one of a space ship from a science fiction film.
Listen to the songs of individual cicadas at close range and you’ll hear a difference between the widespread M. septendecim “Pharaoh Periodical Cicada” and the other two species. M. septendecim‘s song is often characterized as a drawn out version of the word “Pharaoh”, hence the species’ unofficial common name. As part of their courtship ritual, “Pharaoh Periodical Cicadas” sometimes make a purring or cooing sound, which is often extended to sound like kee-ow, then sometimes revved up further to pha-raoh. M. cassinii, often known as “Cassin’s Periodical Cicada”, and the least common species, M. septendecula, often make scratchy clicking or rattling calls as a lead-in to their song. Most observers will find little difficulty locating the widespread M. septendecim “Pharaoh Periodical Cicada” by sound, so listening for something different—the clicking call—is an easy way to zero in on the two less common species.
To penetrate the droning choruses of large numbers of “Pharaoh” and/or “Cassin’s Periodical Cicadas”, sparingly distributed M. septendecula cicadas have a noise-penetrating song consisting of a series of quick raspy notes with a staccato rhythm reminiscent of a pulsating lawn sprinkler. It can often be differentiated by a listener even in the presence of a roaring chorus of one or both of the commoner species. However, a word of caution is due. To call in others of their kind, “Cassin’s Periodical Cicadas” can produce a courtship song similar to that of M. septendecula so that they too can penetrate the choruses of the enormous numbers of “Pharaoh Periodical Cicadas” that concentrate in many areas. To play it safe, it’s best to have a good look at the cicadas you’re trying to identify.
M. cassinii Periodical Cicadas “singing” from a treetop at Colebrook, Lebanon County, Pennsylvania. Clicking phrases are sure sign of the presence of this species and/or M. septendecula, the least likely of the three species to be encountered. When in close proximity to a swarm, a listener will often notice the rising and falling volume of a chorus in a cycle that repeats every few seconds, an effect caused by cicadas attempting to synchronize their songs in a harmony with others in the group. When courtship and mating is complete, female Periodical Cicadas will begin laying eggs in slits made in fresh new growth at the ends of branches on deciduous trees like the one seen here.
Visually identifying Brood X Periodical Cicadas to the species level is best done by looking for two key field marks—first, the presence or absence of orange between the eye and the root of the wings, and second, the presence or absence of orange bands on the underside of the abdomen. Seeing these field marks clearly requires in-hand examination of the cicada in question.
Observing a perched Brood X Periodical Cicada can sometimes provide a view of the key field marks needed for identification of the species. On the M. septendecim “Pharaoh Periodical Cicada” seen here, the orange patch between the eye and wing root and the orange bands on the underside of the abdomen are visible.The abdomen of this perched M. cassinii “Cassin’s Periodical Cicada” appears, when viewed through the wings, to have orange bands. But, examination in hand would show an all-black abdomen with glossy surfaces shining in the sunlight. For accuracy, the up-close-and-personal look is necessary.In the hand, cicadas can be better studied for key field marks. M. septendecim (top) is larger than M. cassini (bottom) and M. septendecula, but the difference is not always apparent, particularly when a direct comparison cannot be made.
To reliably separate Brood X Periodical Cicadas by species, it is necessary to get a closeup view of the section of the thorax between the eye and the root (insertion) of the wings, plus a look at the underside of the abdomen. Here’s what you’ll see…
M. septendecim has an orange patch between the eye and the root of the wings.The underside of M. septendecim’s abdomen has orange bands or stripes along the trailing edge of each segment. The width of the bands can vary, but is typically wider on males (left) than on females (right).
Magicicada cassinii—“Cassin’s Periodical Cicada”
The thorax of M. cassinii is black between the eye and the wing insertion.The underside of M. cassinii’s abdomen is all black without orange bands or stripes in both the male (left) and female (right).
Magicicada septendecula
M. septendecula’s thorax is black between the eye and root of the wings.The underside of M. septendecula’s abdomen has narrow orange bands or stripes along the trailing edge of each segment. The width of the bands can differ. Those of this male (left) are minimal and the bands on this female (right) are near the maximum for the species.
There you have it. Get out and take a closer look at the Brood X Periodical Cicadas near you.
The abundant and widespread “Pharaoh Periodical Cicada” (M. septendecim).It’ll all be over before long. Accumulating remains of M. cassinii “Cassin’s Periodical Cicadas” beneath an Eastern White Pine at the site of the Colebrook State Game Lands swarm.
The Magi have arrived. Emanating from the shadows of a nearby forest, you may hear the endless drone of what sounds like an extraterrestrial craft. Then you get your first look at those beady red eyes set against a full suit of black armor—out of this world. The Magicicada are here at last.
This exuvia, the leftover from a cicada’s final molt, tells us they are here.A Brood X Periodical Cicada soon after emergence and final molt.Not to worry, cicadas are harmless and docile when handled. This is Magicicada septendecim, the largest and most common of our three species of Brood X seventeen-year cicadas. They are currently emerging along south-facing borders of forests and wooded parks and lawns.Magicicada septendecim can be recognized by the orange on the thorax behind each eye and in front of the wing insertions. The smaller M. cassinii and M. septendecula have no orange coloration between the eye and wing.Magicicada septendecim (seen here) has broad orange stripes on the abdomen. M. cassinii has an all black abdomen and M. septendecula, the rarest species, has narrow well-defined orange stripes.
If you go out and about to observe Periodical Cicadas, keep an eye open for these species too…
Spotted Lanternflies, one of our most dreaded invasive species, have hatched. These tiny nymphs about 5 millimetres in length were found feeding on a Virginia Creeper (Parthenocissus quinquefolia), a native vine in the grape family (Vitaceae).Deer Ticks, also known as Black-legged Ticks, are hanging around on vegetation of all kinds looking to hitch a ride on a suitable host. Don’t let it be you. This adult female, less than 5 millimetres in length, was washed loose during an after-hike shower.
Back in the spring of 2004, members of the Tri-County Conewago Creek Association (T.C.C.C.A.), a non-profit conservation group founded to improve water quality in Conewago Creek and its tributaries in Dauphin, Lancaster, and Lebanon Counties in Pennsylvania, were, in order to better understand the status of the flora and fauna in the watershed, frequently spending their weekends surveying the animal and plant life found in the drainage basin’s forests, streams, and farmlands. This effort identified populations of several species of concern and helped supplement the more formal assessment that was used to determine the placement, scale, and scope of projects needed to reduce nutrient and erosion impairment in the Conewago’s waterways.
These regular outings happened to coincide with the Brood X Periodical Cicada emergence of 2004. Back then, as the record keeper for the T.C.C.C.A.’s weekly survey forays, your editor decided to shade a map of the Conewago Creek Watershed showing where the group’s volunteers encountered choruses of the Brood X cicadas. Fortunately, the map is still in the editor’s pile of stuff, and is reproduced here for you.
T.C.C.C.A.’s brochure map of the Conewago Creek Watershed (the Conewago east of the Susquehanna River), shaded with red ink in 2004 indicating locations where noisy choruses of Brood X Periodical Cicadas were found. The range of the insects closely mirrors the forested areas of the watershed. The nearly contiguous range along the southeast border includes the heavily wooded areas of Mount Gretna, State Game Lands 145, and the northwest slope of the diabase ridge that separates the Conewago from neighboring watersheds in Lancaster County.
A notation on the map (visible just above the cap on the pen) indicates May 16 as the emergence date for the cicadas in 2004—seventeen years ago today.
So why no seventeen-year cicadas yet in 2021? The answer is ground temperature. This year, by mid-April, Brood X Periodical Cicadas were just below the leaves and rocks, ready to break the surface. But a cold month since then has stalled their emergence. A thermometer pushed into the forest soil today showed readings of 60 degrees and less—at least four degrees below the temperature needed to get the nymphs crawling out of the dirt to climb rocks and vegetation where they’ll molt, dry, and take flight.
In the forested hills east of Conewago Falls, in the Conewago Creek Watershed, soil temperatures were as low as 54 degrees Fahrenheit today.
A warm week ahead with daytime temperatures in the eighties and nighttime lows in the fifties and sixties, instead of in the forties, should get the woodland soils warming. Brood X Periodical Cicadas will be out and about in a jiffy—and you’ll hear all about it.
Meet the Double-crested Cormorant, a strangely handsome bird with a special talent for catching fish. You see, cormorants are superb swimmers when under water—using their webbed feet to propel and maneuver themselves with exceptional speed in pursuit of prey.
Like many species of birds that dive for their food, Double-crested Cormorants run across the surface of the water to gain speed for a takeoff. Smaller wings may make it more difficult to get airborne, but when folded, they provide improved streamlining for submerged swimming.
Double-crested Cormorants, hundreds of them, are presently gathered along with several other species of piscivorous (fish-eating) birds on the lower Susquehanna River below Conowingo Dam near Rising Sun, Maryland. Fish are coming up the river and these birds are taking advantage of their concentrations on the downstream side of the impoundment to provide food to fuel their migration or, in some cases, to feed their young.
Double-crested Cormorants, mostly adult birds migrating toward breeding grounds to the north, are gathered on the rocks on the east side of the river channel below Conowingo Dam. A Great Blue Heron from a nearby rookery can be seen at the center of the image.Bald Eagles normally gather in large numbers at Conowingo Dam in the late fall and early winter. Presently there are more than 50 there, and the majority of them are breeding age adults. Presumably they are still on their way north to nest. Meanwhile, local pairs are already feeding young, so it seems these transient birds are running a bit late. Many of them can be seen on the rocks along the east side of the river channel,……on the powerline trestles on the island below the dam……in the trees along the east shore,……and in the trees surrounding Fisherman’s Park on the west shore.
In addition to the birds, the movements of fish attract larger fish, and even larger fishermen.
Anglers gather to fish the placid waters below the dam’s hydroelectric powerhouse . Only a few of the generating turbines are operating, so the flow through the dam is minimal.Some water is being released along the west shoreline to attract migratory river herring to the west fish lift for sorting and retention as breeding stock for a propagation program. The east lift, the passage that hoists American Shad (Alosa sapidissima) to a trough that allows them to swim over the top of the dam to waters upriver, will begin operating as soon as these larger migratory fish begin arriving.
The excitement starts when the sirens start to wail and the red lights begin flashing. Yes friends, it’s showtime.
Red lights and sirens are a warning that additional flow is about to be released from the dam. Boaters should anticipate rough water and persons in and along the river need to seek higher ground immediately.Gates are opened at mid-river to release a surge of water through the dam.The wake from the release quickly reaches the shoreline, raising the water level in moments.Experienced anglers know that the flow through the dam gets fish moving and can improve the catch significantly, especially in spring when many species are ascending the river.
Within minutes of the renewed flow, birds are catching fish.
A Double-crested Cormorant with a young Channel Catfish (Ictalurus punctatus).A Double-crested Cormorant fleeing others trying to steal its Channel Catfish.Another Double-crested Cormorant eating a Channel Catfish. Did you realize that Channel Catfish were an introduced species in the Susquehanna River system?An Osprey with a stick, it’s too busy building a nest right now to fish.Great Blue Herons swallow their prey at the spot of capture, then fly back to the nest to regurgitate a sort of “minced congealed fish product” to their young.
Then the anglers along the wave-washed shoreline began catching fish too.
This young man led off a flurry of catches that would last for the remainder of the afternoon.Though Gizzard Shad are filter feeders that don’t readily take baits and lures, they are regularly foul-hooked and reeled in from the large schools that ascend the river in spring.Gizzard Shad are very abundant in the lower Susquehanna, providing year-round forage for many species of predatory animals including Bald Eagles.A Double-crested Cormorant swallowing a Gizzard Shad.This angler soon helped another fisherman by landing his large catch, a Northern Snakehead (Channa argus).The teeth of a Northern Snakehead are razor sharp. It is an aggressive non-native invasive species currently overtaking much of the Lower Susquehanna River Watershed. Anglers are encouraged to fish for them, catch them, keep them, and kill them at the site of capture. Never transport a live Northern Snakehead anywhere at any time. It is illegal in both Maryland and Pennsylvania to possess a live snakehead. Northern Snakehead advisory sign posted at Exelon Energy’s Conowingo Fishermen’s Park.A stringer of Northern Snakeheads. This species was imported from Asia as a food fish, so it has excellent culinary possibilities. It’s better suited for a broiler or frying pan than a river or stream.Another stringer of Northern Snakeheads. It’s pretty safe to say that they have quickly become one of the most abundant predatory fish in the river. Their impact on native species won’t be good, so catch and eat as many as you can. Remember, snakeheads swim better in butter and garlic than in waters with native fish.This foul-hooked Shorthead Redhorse (Moxostoma macrolepidotum), a native species of sucker, was promptly released.Striped Bass are anadromous fish that leave the sea in spring to spawn in fresh water. They ascend the Susquehanna in small numbers, relying upon the operation of the fish passages at the Conowingo, Holtwood, Safe Harbor, and York Haven Dams to continue their journey upstream. During spring spawning, Striped Bass in the Susquehanna River and on the Susquehanna Flats portion of the upper Chesapeake Bay are not in season and may not be targeted, even for catch-and-release. This accidental catch was immediately turned loose.After removal from the hook, this hefty Smallmouth Bass was returned to the river. Many anglers are surprised to learn that Smallmouth Bass are not native to the Susquehanna basin.This angler’s creel contains a Northern Snakehead (left) and a Walleye (right). Did you know that the Walleye (Sander vitreus) is an introduced species in the Susquehanna watershed?By late afternoon, anglers using shad darts began hooking into migrating Hickory Shad (Alosa mediocris), a catch-and-release species in Maryland.Hickory Shad are recognized by their lengthy lower jaw. They are anadromous herring that leave the sea to spawn in freshwater streams. Hickory Shad ascend the Susquehanna as far as Conowingo Dam each year, but shy away from the fish lifts. Downriver from the dam, they do ascend Deer Creek along the river’s west shore and Octoraro Creek on the east side. In Pennsylvania, the Hickory Shad is an endangered species.A Hickory Shad angled on a dual shad dart rig. During the spring spawning run, they feed mostly on small fish, and are the most likely of the Susquehanna’s herring to take the hook.Simultaneous hook-ups became common after fours hours worth of release water from the dam worked its way toward the mouth of the river and got the schools moving. Water temperatures in the mid-to-upper-fifties trigger the ascent of Hickory Shad. On the Susquehanna, those temperatures were slow to materialize in the spring of 2021, so the Hickory Shad migration is a bit late.Catch-and-release fishing for Hickory Shad appears to be in full swing not only at the dam, but along the downstream shoreline to at least the mouth of Deer Creek at Susquehanna State Park too.Many Hickory Shad could be seen feeding on some of the millions of caddisflies (Trichoptera) swarming on the river. These insects, along with earlier hatches of Winter Stoneflies (Taeniopterygidae), not only provide forage for many species of fish, but are a vital source of natural food for birds that migrate up the river in March and April each year. Swallows, Ring-billed Gulls, and Bonaparte’s Gulls are particularly fond of snatching them from the surface of the water.A Winter Stonefly (Taeniopterygidae) from an early-season hatch on the Susquehanna River at the Veteran’s Memorial Bridge at Columbia/Wrightsville, Pennsylvania. (March 3, 2021)Just below Conowingo Dam, a lone fly fisherman was doing a good job mimicking the late-April caddisfly hatch, successfully reeling in numerous surface-feeding Hickory Shad.You may have noticed the extraordinary number of introduced fish species listed in this account of a visit to Conowingo Dam. Sorry to say that there are two more: the Flathead Catfish (Pylodictis olivaris) and the Blue Catfish (Ictalurus furcatus). Like the Northern Snakehead, each has become a plentiful invasive species during recent years. Unlike the Northern Snakehead, these catfish are “native transplants”, species introduced from populations in the Mississippi River and Gulf Slope drainages of the United States. So if you visit the area, consider getting a fishing license and catching a few. Like the snakeheads, they too are quite palatable.
The arrival of migrating Hickory Shad heralds the start of a movement that will soon include White Perch, anadromous American Shad, and dozens of other fish species that swim upstream during the springtime. Do visit Fisherman’s Park at Conowingo Dam to see this spectacle before it’s gone. The fish and birds have no time to waste, they’ll soon be moving on.
To reach Exelon’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road. Drive down the hill to the parking area along the river. The park’s address is 2569 Shureslanding Road, Darlington, Maryland.
A water release schedule for the Conowingo Dam can be obtained by calling Exelon Energy’s Conowingo Generation Hotline at 888-457-4076. The recording is updated daily at 5 P.M. to provide information for the following day.
And remember, the park can get crowded during the weekends, so consider a weekday visit.
Yesterday, a hike through a peaceful ridgetop woods in the Furnace Hills of southern Lebanon County resulted in an interesting discovery. It was extraordinarily quiet for a mid-April afternoon. Bird life was sparse—just a pair of nesting White-breasted Nuthatches and a drumming Hairy Woodpecker. A few deer scurried down the hillside. There was little else to see or hear. But if one were to have a look below the forest floor, they’d find out where the action is.
Not much action in the deer-browsed understory of this stand of hardwoods.Upon discovery beneath a rock, this invertebrate quickly backed its way down the burrow, promptly seeking shelter in the underground section of the excavation.A closeup of the same image reveals the red eyes of this Periodical Cicada (Magicicada species) nymph. It has reached the end of seventeen years of slowly feeding upon the sap from a tree root to nourish its five instars (stages) of larval development.
2021 is an emergence year for Brood X, the “Great Eastern Brood”—the largest of the 15 surviving broods of Periodical Cicadas. After seventeen years as subterranean larvae, the nymphs are presently positioned just below ground level, and they’re ready to see sunlight. After tunneling upward from the deciduous tree roots from which they fed on small amounts of sap since 2004, they’re awaiting a steady ground temperature of about 64 degrees Fahrenheit before surfacing to climb a tree, shrub, or other object and undergo one last molt into an imago—a flying adult.
Here, approximately one dozen Periodical Cicada nymphs have tunneled into pre-emergence positions beneath a rock. Seventeen-year Periodical Cicadas, sometimes mistakenly called “seventeen-year locusts”, are the longest-lived of our insects.Note the wings and red eyes beneath the exoskeleton of this Periodical Cicada nymph. Within weeks it will join billions of others in a brief emergence to molt, dry, fly, mate, and die.Adult (imago) Periodical Cicadas. Brood X includes all three species of seventeen-year Periodical Cicadas: Magicicada septendecim, M. cassinii, and M. septendecula. All Periodical Cicadas in the United States are found east of the Great Plains, the lack of trees there prohibiting the expansion of their range further west. Seventeen-year life cycles account for twelve of the fifteen broods of Periodical Cicadas; the balance live for thirteen years. The range of Brood X includes the lower Susquehanna basin and parts of Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, Ohio, Tennessee, Virginia, West Virginia, and the District of Columbia. (United States Department of Agriculture/Agricultural Research Service image)The flight of Periodical Cicadas peaks in late-May and June. Shown here is the Eastern Scissor Grinder, an “Annual Cicada” that emerges later in the season, peaking yearly during July and August.
The woodlots of the Lower Susquehanna River Watershed won’t be quiet for long. Loud choruses of male Periodical Cicadas will soon roar through forest and verdant suburbia. They’re looking for love, and they’re gonna die trying to find it. And dozens and dozens of animal species will take advantage of the swarms to feed themselves and their young. Yep, the woods are gonna be a lively place real soon.
Did you say Periodical Cicadas? We can hardly wait!
Let’s take a quiet stroll through the forest to have a look around. The spring awakening is underway and it’s a marvelous thing to behold. You may think it a bit odd, but during this walk we’re not going to spend all of our time gazing up into the trees. Instead, we’re going to investigate the happenings at ground level—life on the forest floor.
Rotting logs and leaf litter create the moisture retaining detritus in which mesic forest plants grow and thrive. Note the presence of mosses and a vernal pool in this damp section of forest.The earliest green leaves in the forest are often those of the Skunk Cabbage (Simplocarpus foetidus). This member of the arum family gets a head start by growing in the warm waters of a spring seep or in a stream-fed wetland. Like many native wildflowers of the forest, Skunk Cabbage takes advantage of early-springtime sun to flower and grow prior to the time in late April when deciduous trees grow foliage and cast shade beneath their canopy.Among the bark of dead and downed trees, the Mourning Cloak butterfly (Nymphalis antiopa) hibernates for the winter. It emerges to alight on sun-drenched surfaces in late winter and early spring.Another hibernating forest butterfly that emerges on sunny early-spring days is the Eastern Comma (Polygonia comma), also known as the Hop Merchant.In a small forest brook, a water strider (Gerridae) chases its shadow using the surface tension of the water to provide buoyancy. Forests are essential for the protection of headwaters areas where our streams get their start.Often flooded only in the springtime, fish-free pools of water known as vernal ponds are essential breeding habitat for many forest-dwelling amphibians. Unfortunately, these ephemeral wetland sites often fall prey to collecting, dumping, filling, and vandalism by motorized and non-motorized off-roaders, sometimes resulting in the elimination of the populations of frogs, toads, and salamanders that use them.Wood Frogs (Lithobates sylvaticus) emerge from hiding places among downed timber and leaf litter to journey to a nearby vernal pond where they begin calling still more Wood Frogs to the breeding site.Wood Frog eggs must hatch and tadpoles must transform into terrestrial frogs before the pond dries up in the summertime. It’s a risky means of reproduction, but it effectively evades the enormous appetites of fish.When the egg laying is complete, adult Wood Frogs return to the forest and are seldom seen during the rest of the year.In early spring, Painted Turtles emerge from hideouts in larger forest pools, particularly those in wooded swamps, to bask in sunny locations.Dead standing trees, often called snags, are essential habitats for many species of forest wildlife. There is an entire biological process, a micro-ecosystem, involved in the decay of a dead tree. It includes fungi, bacteria, and various invertebrate animals that reduce wood into the detritus that nourishes and hydrates new forest growth.Birds like this Red-headed Woodpecker feed on insects found in large snags and nest almost exclusively in them. Many species of wildlife rely on dead trees, both standing and fallen, during all or part of their lives.
There certainly is more to a forest than the living trees. If you’re hiking through a grove of timber getting snared in a maze of prickly Multiflora Rose (Rosa multiflora) and seeing little else but maybe a wild ungulate or two, then you’re in a has-been forest. Logging, firewood collection, fragmentation, and other man-made disturbances inside and near forests take a collective toll on their composition, eventually turning them to mere woodlots. Go enjoy the forests of the lower Susquehanna valley while you still can. And remember to do it gently; we’re losing quality as well as quantity right now—so tread softly.
The White-tailed Deity in a woodlot infested by invasive tangles of Multiflora Rose.
Early October is prime time for hawk watching, particularly if you want to have the chance to see the maximum variety of migratory species. In coming days, a few Broad-winged Hawks and Ospreys will still be trickling through while numbers of Sharp-shinned Hawks, Cooper’s Hawks, Northern Harriers, and falcons swell to reach their seasonal peak. Numbers of migrating Red-tailed and Red-shouldered Hawks are increasing during this time and late-season specialties including Golden Eagles can certainly make a surprise early visit.
If you enjoy the outdoors and live in the southernmost portion of the lower Susquehanna valley, Rocky Ridge County Park in the Hellam Hills just northwest of York, Pennsylvania, is a must see. The park consists of oak forest and is owned and managed by the York County Parks Department. It features an official hawk watch site staffed by volunteers and park naturalists. Have a look.
The hawk watch lookout is reached by following the well-marked trail at the north side of the large gravel parking area in the utility right-of-way at the end of the park entrance road (Deininger Road).The Rocky Ridge Hawk Watch lookout includes outcrops of bedrock, a viewing deck, and grassy areas suitable for lawn chairs.The bedrock at the lookout is an unusual quartz-cemented conglomerate that forms the Hellam Member at the base of the Cambrian Chickies Formation.Experienced hawk watchers conduct an official count of raptors and other birds during the autumn migration in September and October each year. Visitors are welcome. The view is spectacular. Check out the concrete columns glowing in the sun to the north of the lookout.It’s the cooling towers at the Three Mile Island Nuclear Station and the smoke stacks at the Brunner Island Steam Generating Station. Conewago Falls is located between the two.Interpretive signage on the hawk watch deck includes raptor identification charts.A migrating Osprey glides by the lookout.Throughout the month, migrating Sharp-shinned Hawks will be flying in a southwesterly direction along ridges in the region, particularly on breezy days. They are the most numerous raptor at hawk watches in the lower Susquehanna valley during the first half of October.A Peregrine Falcon quickly passes the Rocky Ridge lookout. These strong fliers often ignore the benefits provided by thermals and updrafts along our ridges and instead take a direct north to south route during migration.A juvenile Red-tailed Hawk soars by.And a little while later, an adult Red-tailed Hawk follows.Bald Eagles, including both migratory and resident birds, are seen regularly from the Rocky Ridge lookout.Other diurnal (daytime) migrants are counted at Rocky Ridge and some of the other regional hawk watches. Massive flights of Blue Jays have been working their way through the lower Susquehanna valley for more than a week now. Local hawk watches are often logging hundreds in a single day.The utility right-of-way within which the Rocky Ridge Hawk Watch is located can be a great place to see nocturnal (nighttime) migrants while they rest and feed during the day. Right now, Eastern Towhees are common there.An uncommon sight, a shy Lincoln’s Sparrow (Melospiza lincolnii) in the utility right-of-way near the hawk watch lookout. This and other nocturnal migrants will take full advantage of a clear moonlit night to continue their southbound journey.
If you’re a nature photographer, you might be interested to know that there are still hundreds of active butterflies in Rocky Ridge’s utility right-of-way. Here are a few.
A Gray Hairstreak.An American Copper (Lycaena phlaeas),
To see the daily totals for the raptor count at Rocky Ridge Hawk Watch and other hawk watches in North America, and to learn more about each site, be certain to visit hawkcount.org
This morning, the Lower Susquehanna River Watershed experienced remotely the effects of fire and ice.
At daybreak, the cold air mass that brought the first freeze of the season to northernmost New England gave us a taste of the cold with temperatures below 50 degrees throughout.
The air temperature at daybreak in the Gettysburg Basin east of Conewago Falls.
At sunrise, the cloudless sky had a peculiar overcast look with no warm glow on buildings, vegetation, and terrain. Soon, the sun was well above the horizon, yet there was still a sort of darkness across the landscape.
Smoke from massive wildland fires in the Pacific Coast States created a haze that persisted throughout the day in the Susquehanna valley.Away from traffic and the odors of agriculture and urban life, the smell of wood smoke was easily detectable. The haze from fires almost 3,000 miles away made it appear to be an overcast day at Conewago Falls.Due to the sudden cold, there were no insects flying above the Susquehanna during the first hour of daylight this morning, so swallows gathered in the trees to conserve energy until the hunt would be more productive.The diabase boulders at Conewago Falls retain heat and provide an even better refuge from the cold than a dead tree on a chilly morning. Here, a juvenile and an adult Tree Swallow (center) are surrounded by Northern Rough-winged Swallows. Hundreds of each of these migratory species were feeding at the falls today.Two dozen or more Barn Swallows, including this juvenile, were seen among the swarming birds.Several late Bank Swallows, including this one (bottom center), were among the flocks of migrants at Conewago Falls this morning. One Cliff Swallow (Petrochelidon pyrrhonota) was seen as well.A Great Egret (Ardea alba) and a Great Blue Heron.An Osprey searching the clear pools and rapids for a morning meal.A juvenile Bald Eagle with the same goal in mind.The same Bald Eagle keeping a close watch on the Osprey. Bald Eagles frequently ambush Ospreys to steal their catch. For a young eagle, acquiring the skill of fish theft may improve its chances of survival, at least until the Ospreys head south.
All that bright filtered sunlight was ideal for photographing butterflies along the Conewago Falls shoreline. Have a look.
During the late morning, dozens of Monarch butterflies migrated past Conewago Falls. This one paused to feed.The Viceroy (Limenitis archippus) is a Monarch mimic. Its appearance fools would-be predators into thinking it is a Monarch and possesses the same foul flavor as the milkweed-raised model.This Variegated Fritillary (Euptoieta claudia) was among the late-season butterflies at Conewago Falls.The Common Buckeye is presently just that, very common on flowers and moist sandy soil around the falls.The Painted Lady is a regularly-occurring migratory species of butterfly.The Red Admiral is typically a common to abundant migrant. So far in 2020, they are scarce in the lower Susquehanna valley.
If it can fly, there’s a pretty good chance it was at Second Mountain today.
What follows is a photographic chronology of some of today’s sightings at Second Mountain Hawk Watch at Fort Indiantown Gap in Lebanon County, Pennsylvania. We begin with some of the hundreds of migratory songbirds found at the base of the mountain along Cold Spring Road near Indiantown Run during the early morning, then we continue to the lookout for the balance of the day.
A Black-and-white Warbler (Mniotilta varia) searching the trunk of a tree for insects.A Rose-breasted Grosbeak.A Blackburnian Warbler high in the forest canopy.A Black-throated Green Warbler bouncing from branch to branch as it feeds.A Chestnut-sided Warbler lurks among the foliage.A Magnolia Warbler.One of a hundred or more Red-eyed Vireos found swarming the treetops, and occasionally the understory, while engaging in a wild feeding frenzy.A male American Redstart. Judging by that gray hood, it’s probably experiencing its second fall migration.Eyes were skyward at the Second Mountain Hawk Watch lookout as Broad-winged Hawks began streaming through during the mid-morning.During the morning flight, Broad-winged Hawks including this adult floated by the lookout riding updrafts created by the south wind striking the face of the mountain ridge.As the overcast became more scattered and more sunlight reached the ground, Broad-winged Hawks began riding thermal currents to gain altitude before gliding off to the southwest in continuance of their long trip to the tropics. At times, birds would disappear into the base of the clouds before ending their climb and sailing away.Broad-winged Hawks rely principally upon amphibians and large insects like this bush katydid (Scudderia species) for sustenance. With freezing temperatures just around the corner, “broad-wings” must make their way to warmer climes early or risk starvation.A Bald Eagle always gets observers looking.A juvenile Broad-winged Hawk.A juvenile Cooper’s Hawk.A Broad-winged Hawk has a look around.One never quite knows what one may see when having a look around.A Cape May Warbler (Setophaga tigrina) in the lookout hemlock.A Black Saddlebags, one of several migratory dragonflies seen today.An Osprey glides through in the afternoon glare.A speedy Merlin thrilled observers with a close approach.One must remember that Fort Indiantown Gap is an active military installation, so from time to time training and drilling exercises may interrupt bird observation activities at the Second Mountain Hawk Watch.Today, speedy A-10 Warthog attack aircraft piloted by members of the Maryland Air National Guard based at Glenn Martin Field thrilled observers on the lookout with several close passes during their training runs.And repeat.Drill complete.
The total number of Broad-winged Hawks observed migrating past the Second Mountain lookout today was 619. To see the daily raptor counts for Second Mountain and other hawk watches in North America, and to learn more about each site, be sure to visit hawkcount.org
A special message from your local Chinese Mantis (Tenodera sinensis).
Hey you! Yes, you. I pray you’re paying attention to what’s flying around out there, otherwise it’ll all pass you by.
This summer’s hot humid breezes from the south have not only carried swarms of dragonflies into the lower Susquehanna valley, but butterflies too.
So check out these extravagant visitors from south of the Mason-Dixon Line—before my appetite gets the better of me.
In some years, the Sachem, a vagrant from the south, can become the most frequently observed orange skipper in the Susquehanna valley, far outnumbering faltering populations of resident species around lawns, gardens, meadows, and roadsides. 2020 appears to be one of those years.The Fiery Skipper (Hylephila phyleus) sometimes strays north along the lower Susquehanna River in late summer. This one was photographed recently at Conewago Falls.The Cloudless Sulphur is a large fast-flying brilliant yellow butterfly. Here in the Susquehanna valley, it is usually seen singly, though colonizers will breed in patches of Partridge Pea, Wild Senna (Senna hebecarpa), and Maryland Senna (Senna marilandica). Cloudless Sulphurs are really widespread this year. In areas where intensive farming practices are in use, your chances of seeing one of these wandering around right now might be just as good as your chances of seeing one of the diminished flights of the resident Clouded Sulphurs (Colias philodice) and Orange Sulphurs (Colias eurytheme).The Red-banded Hairstreak (Calycopis cecrops) is the least conspicuous of the stray butterflies shown here. This beauty was photographed several days ago along the edge of an oak forest in northern Lancaster County, PA.
There you have it. Get out there and have a look around. These species won’t be active much longer. In just a matter of weeks, our migratory butterflies, including Monarchs, will be heading south and our visiting strays will either follow their lead or risk succumbing to frosty weather.
For more photographs of butterflies, be sure to click the “Butterflies” tab at the top of the page. We’re adding more as we get them.
It’s been more than a week since Tropical Storm Isaias moved swiftly up the Atlantic seaboard leaving wind and flood damage in its wake. Here in the Lower Susquehanna River Watershed, the brevity of its presence minimized the effects.
Tropical Storm Isaias moves north-northeast across the Delmarva Peninsula.
You may have noticed some summertime visitors flying about during these hot humid days that followed Isaias’ passing. They’re the dragonflies.
Our familiar friend the Wandering Glider is widespread throughout the valley right now—dropping eggs on shiny automobile hoods that look to them like a nice quiet puddle of water.
The Wandering Glider is a global traveler. Here in the lower Susquehanna valley, it is currently abundant around still water and in large parking lots.
Each of the other common migratory species is here too. Look for them patrolling the skies over large bodies of water and over adjacent fallow land and meadows where tiny flying insects abound. Did these dragonflies arrive on the winds associated with the tropical storm, or did they move in with the waves of warm air that followed it? Probably a little of both.
The Common Green Darner, a large dragonfly, can be the most abundant of the migratory species. Watch for high-flying swarms in the coming weeks.The Black Saddlebags is recognized in flight by the black base of each hindwing. These patches give the appearance of a pair of saddlebags draped across the dragonfly’s thorax.The Twelve-spotted Skimmer(Libellula pulchella) is a regular migrant.The Prince Baskettail (Epitheca princeps) can occur among mixed groups of dragonflies. Despite it rarely being mentioned as a migrant, its proclivity for non-stop day-long flight makes it a likely sighting among sizeable swarms.
Big swarms of dragonflies don’t go unnoticed by predators—particularly birds. The southbound migration of kites, Broad-winged Hawks, American Kestrels, and Merlins often coincides with the swarming of migratory dragonflies in late summer. Each of these raptors will grab and feed upon these insects while on the wing—so keep an eye on the sky.
This Peregrine Falcon found the congregations of hundreds of dragonflies worthy of a closer look……and an acrobatic fly-by to disrupt the swarms. Fun, fun, fun, fun, fun.
Dust continues to be carried aloft on dry updrafts over the Sahara Desert. The plume is presently stretching for thousands of miles due west across the tropical Atlantic into the Pacific, leaving the United States out of the loop—at least for now.
(CIRA/NOAA image)
With no dry air to spoil the fun, the warm waters of the Gulf Stream off the coast of North Carolina are spawning some convective clouds in a low pressure system that could become tropical within the next day or so.
Tropical or not, it looks like a rainy weekend along the Mid-Atlantic coast. (CIRA/NOAA image)
Now that the heat and humidity is upon us, why not get out and take a look at the damselflies and dragonflies that inhabit the ponds, wetlands, and waterways of the lower Susquehanna watershed? These flying insects thrive in sultry weather and some species will breed in a body of water as small as a garden pond—as long as it is free of large fish. Check out some of the species found locally by clicking on the “Damselflies and Dragonflies” tab at the top of this page. We’ll be adding more photos and species soon.
Inside the doorway that leads to your editor’s 3,500 square foot garden hangs a small chalkboard upon which he records the common names of the species of birds that are seen there—or from there—during the year. If he remembers to, he records the date when the species was first seen during that particular year. On New Year’s Day, the results from the freshly ended year are transcribed onto a sheet of notebook paper. On the reverse, the names of butterflies, mammals, and other animals that visited the garden are copied from a second chalkboard that hangs nearby. The piece of paper is then inserted into a folder to join those from previous New Year’s Days. The folder then gets placed back into the editor’s desk drawer beneath a circular saw blade and an old scratched up set of sunglasses—so that he knows exactly where to find it if he wishes to.
A quick glance at this year’s list calls to mind a few recollections.
The 2019 bird list included 48 species, the 47 on the board plus Ruby-throated Hummingbird, which was logged on a slip of paper found tucked into the edge of the frame.
This Green Frog, photographed on New Year’s Day 2019, was “out and about” along the edge of the editor’s garden pond. Due to the recent mild weather, Green Frogs were active during the current New Year’s holiday as well.On a day with strong south winds in late February or during the first two weeks of March, there is often a conspicuous northbound spring flight of migrating waterfowl, gulls, and songbirds that crosses the lower Susquehanna valley as it departs Chesapeake Bay. These Tundra Swans were among the three thousand seen from the garden patio on March 13, 2019. A thousand migrating Canada Geese, 500 Red-winged Blackbirds, numerous Ring-billed Gulls, and some Herring Gulls were seen during the same afternoon.This juvenile Cooper’s Hawk was photographed through the editor’s kitchen window. From its favorite perch on this arbor it would occasionally find success snagging a House Sparrow from the large local flock. It first visited the garden in November, the species being absent there since early spring. Unlike previous years, there was no evidence of a breeding pair in the vicinity during 2019.Plantings that provide food and cover for wildlife are essential to their survival. Native flowers including Trumpet Vine (Campsis radicans) and Partridge Pea provide nourishment for the Ruby-throated Hummingbirds that visit the editor’s garden, but they really love a basket or pot filled with Mexican Cigar (Cuphea ignea) too. The latter (seen here) can be grown as a houseplant and moved outdoors to a semi-shaded location in summer and early fall. But remember, it’s tropical, so you’ll need to bring it back inside when frost threatens.A Swamp Sparrow is an unusual visitor to a small property surrounded by paved parking lots and treeless lawns. Nevertheless, aquatic gardens and native plants helped to attract this nocturnal migrant, seen here eating seeds from Indiangrass. It arrived on September 30 and was gone on October 2.
Before putting the folder back into the drawer for another year, the editor decided to count up the species totals on each of the sheets and load them into the chart maker in the computer.
Despite the habitat improvements in the garden, the trend is apparent. Bird diversity has not cracked the 50 species mark in 6 years. Despite native host plants and nectar species in abundance, butterfly diversity has not exceeded 10 species in 6 years.
It appears that, at the very least, the garden habitat has been disconnected from the home ranges of many species by fragmentation. His little oasis is now isolated in a landscape that becomes increasingly hostile to native wildlife with each passing year. The paving of more parking areas, the elimination of trees, shrubs, and herbaceous growth from the large number of rental properties in the area, the alteration of the biology of the nearby stream by hand-fed domestic ducks, light pollution, and the outdoor use of pesticides have all contributed to the separation of the editor’s tiny sanctuary from the travel lanes and core habitats of many of the species that formerly visited, fed, or bred there. In 2019, migrants, particularly “fly-overs”, were nearly the only sightings aside from several woodpeckers, invasive House Sparrows (Passer domesticus), and hardy Mourning Doves. Even rascally European Starlings became sporadic in occurrence—imagine that! It was the most lackluster year in memory.
The Tufted Titmouse was a daily visitor to the garden through 2018. This one was photographed investigating holes in an old magnolia there during the spring of that year. There were no Tufted Titmouse sightings in the garden in 2019. This and other resident species, especially cavity-nesters, appear to be experiencing at least a temporary decline.Breeding birds including Northern Cardinals may have had a difficult year. In the editor’s garden, a pair were still feeding and escorting one of their young in early October. The infestation of the editor’s town by domestic house and feral cats may have contributed to the failure of earlier broods, but a lack of food is also a likely factor.
If habitat fragmentation were the sole cause for the downward trend in numbers and species, it would be disappointing, but comprehendible. There would be no cause for greater alarm. It would be a matter of cause and effect. But the problem is more widespread.
Although the editor spent a great deal of time in the garden this year, he was also out and about, traveling hundreds of miles per week through lands on both the east and the west shores of the lower Susquehanna. And on each journey, the number of birds seen could be counted on fingers and toes. A decade earlier, there were thousands of birds in these same locations, particularly during the late summer.
At about the time of summer solstice in June each year, Common Grackles begin congregating into roving summer flocks that will grow in size to assure their survival during the autumn migration, winter season, and return north in the spring. From his garden, the editor saw just one flock of less than a dozen birds during the summer of 2019. He saw none during his journeys through other areas of the Susquehanna valley. Flocks of one hundred birds or more did not materialize until the southbound movements of grackles passed through the region in October and November.
In the lower Susquehanna valley, something has drastically reduced the population of birds during breeding season, post-breeding dispersal, and the staging period preceding autumn migration. In much of the region, their late-spring through summer absence was, in 2019, conspicuous. What happened to the tens of thousands of swallows that used to gather on wires along rural roads in August and September before moving south? The groups of dozens of Eastern Kingbirds (Tyrannus tyrannus) that did their fly-catching from perches in willows alongside meadows and shorelines—where are they?
Several studies published during the autumn of 2019 have documented and/or predicted losses in bird populations in the eastern half of the United States and elsewhere. These studies looked at data samples collected during recent decades to either arrive at conclusions or project future trends. They cite climate change, the feline infestation, and habitat loss/degradation among the factors contributing to alterations in range, migration, and overall numbers.
There’s not much need for analysis to determine if bird numbers have plummeted in certain Lower Susquehanna Watershed habitats during the aforementioned seasons—the birds are gone. None of these studies documented or forecast such an abrupt decline. Is there a mysterious cause for the loss of the valley’s birds? Did they die off? Is there a disease or chemical killing them or inhibiting their reproduction? Is it global warming? Is it Three Mile Island? Is it plastic straws, wind turbines, or vehicle traffic?
The answer might not be so cryptic. It might be right before our eyes. And we’ll explore it during 2020.
A clean slate for 2020.
In the meantime, Uncle Ty and I going to the Pennsylvania Farm Show in Harrisburg. You should go too. They have lots of food there.
With autumn coming to a close, let’s have a look at some of the fascinating insects (and a spider) that put on a show during some mild afternoons in the late months of 2019.
Bush Katydids (Scudderia species) are found in brushy habitats and along rural roadsides. Their green summer color fades to brown, maroon, and gold to match the autumn foliage where they hide. Bush katydids often remain active until a hard freeze finally does them in.The Eastern Buck Moth (Hemileuca maia) is fuzzy, appearing to wear a warm coat for its autumn expeditions. Adults emerge in October and may fly as late as December. Females deposit their eggs on the twigs of Bear Oak (Quercus ilicifolia), Blackjack Oak (Q. marilandica), or Chestnut Oak (Q. montana), trees that, in our region, seem most favorable for the moth’s use when growing on burned barrens and mountain slopes. The spiny caterpillars are known to feed only on the foliage of these few trees. In the lower Susquehanna valley, the Eastern Buck Moth is rare because its specialized habitat is in short supply, and it’s all Smokey The Bear’s fault.The Sachem (Atalopedes campestris) wanders north from the Atlantic Coastal Plain into the Susquehanna valley each summer. In some years they become the most numerous small orange butterfly of all, particularly around home gardens. The larvae will feed on Crabgrass (Digitaria species), but have not found success overwintering this far north. By November, adults begin to look pretty drab.From 1978 through 1982, the Asian Multicolored Lady Beetle (Harmonia axyridis) was introduced into the eastern states by the United States Department of Agriculture. It has become a nuisance in many areas where it swarms, sometimes bites, and often overwinters in large smelly masses within homes and other warm buildings. As you may have guessed, it’s possibly displacing some of the less aggressive native lady beetle species.On a chilly afternoon, a sun-warmed Bold Jumping Spider (Phidippus audax) pounced and dispatched this sluggish worker Honey Bee (Apis mellifera) that was trying to gather pollen from a late-season Purple Coneflower bloom. This spider is bold indeed.Under bridges, inside bird nest boxes, and sometimes beneath porches, the female Pipe Organ Mud Dauber (Trypoxylon politum), a predatory wasp, builds these elaborate nests composed of long rows (pipes) of nursery cells. Into each cell one or more paralyzed spiders is deposited along with one of the female’s eggs. When hatched, each larva will feed upon the paralyzed spider(s) inside its cell, then pupate. The pupae overwinter, then emerge from their cells as adults during the following spring. In the autumn, males often stand guard at an entrance to the nest to prevent parasitic species, including some flies (look at the fifth pipe from the right), from laying eggs on the pupae. These wasps are not aggressive toward humans.A Black-and-yellow Mud Dauber (Sceliphron caementarium) observes a neighboring nest of Common Paper Wasps (Polistes exclamans). The Common Paper Wasp, a species also known as the Guinea Paper Wasp, is a native of the southern United States. It is currently expanding its range into the lower Susquehanna valley from the Atlantic Coastal Plain. These two wasp species and the Pipe Organ Mud Dauber are known to regularly coexist. All three will take advantage of man-made structures for their nest sites. People using the picnic tables beneath this pavilion roof never noticed the hundreds of docile wasps above.Those moody Eastern Yellowjackets (Vespula maculifrons) can get very temperamental during warm autumn days. These wasps may appear to have no enemies, but away from areas impacted by man’s everyday activities, they do. The Robber Fly (Promachus species) hunts like a flycatcher or other woodland bird, waiting on a perch along the forest’s edge for prey to pass by, then ambushing it, yellowjackets included.The invasive Spotted Lanternfly, a native of eastern Asia, continues to spread destruction. It established itself throughout much of the east side of the lower Susquehanna River during the summer and fall of 2019. Their route of travel across the farmlands of the region intersects with plenty of vineyards to obliterate and few, if any, natural enemies. Expect them to begin colonizing the west shore en masse during 2020.In 2020, plan to roll a few Spotted Lanternflies over, enjoy the view, and wait for the crimson tide to pass. With any luck, they’ll peak in a year or two.
SOURCES
Eaton, Eric R., and Kenn Kaufman. 2007. Kaufman Field Guide to Insects of North America. Houghton Mifflin Company. New York, NY.
It’s that time of year when one may expect to find migratory Neotropical songbirds feeding among the foliage of trees and shrubs in the forests, woodlots, and thickets of the lower Susquehanna valley.
During a late afternoon stroll through a headwaters forest east of Conewago Falls outside Mount Gretna, I was pleased to finally come upon a noisy gathering of about two dozen birds. It had, previous to that, been a quiet two hours of walking, only the rumble of an approaching thunderstorm punctuated the silence. Among this little flock were some chickadees, robins, Gray Catbirds, an Eastern Towhee (Pipilo erythrophthalmus), and a Hairy Woodpecker (Dryobates villosus). Besides the catbirds, there were two other species of Neotropical migrants; both were warblers. No less than six Black-throated Blue Warblers (Setophaga caerulescens) were vying for positions in the trees from which they could investigate the stranger on the footpath below. And among the understory shrubs there were at least as many Ovenbirds (Seiurus aurocapilla) satisfying a similar curiosity.
The Black-throated Blue Warbler nests to the north of the lower Susquehanna valley, which it transits as a common spring and fall migrant. On their wintering grounds, they have a thing for warm weather and the better part of a P.B. & J. sandwich.Throughout the Susquehanna watershed, the Ovenbird is a common ground-nesting species in deciduous forests with moderately vegetated understories. The birds seen today may have been a family group that has not yet begun the journey south.
When they depart the Susquehanna valley, these two warbler species will be southbound for wintering ranges that include Florida, many of the Caribbean Islands, Central America, and, for the Ovenbirds, northern South America. Their flights occur at night. During the breeding season and while migrating, both feed primarily on insects and other arthropods . On the wintering grounds, they will consume some fruit. It is during their time in the tropics that the Black-throated Blue Warbler sometimes visits feeding stations that offer grape jelly, much to the delight of bird enthusiasts.
Black-throated Blue Warblers and Ovenbirds commonly winter on the Florida peninsula and in the Bahamas. With the major tropical cyclone Hurricane Dorian presently ripping through the region, these birds are better off taking their time getting there. There’s no need to hurry. The longer they and the other Neotropical migrants hang around, the more we get to enjoy them anyway. So get out there to see them before they go—and remember to look up.
Category 4 Hurricane Dorian at 9:06 EDT on September 2, 2019. If you’re headed that direction, there’s no need to hurry. Note the cloud-free skies over much of the mainland. (NOAA National Environmental Satellite, Data, and Information Service image)A massive bird migration is indicated on Doppler radar in the clear skies over the eastern United States tonight (blue and green over most of the mainland). In this loop of composite radar images from the southeastern states, note the relative absence of a flight over the Florida peninsula where the outer precipitation bands of Hurricane Dorian can be seen. Note too that there appears to be a heavy concentration of birds flying in a southwest direction to cross the Gulf of Mexico, thus continuing their journey to Central or South America while avoiding the deadly hurricane and a much smaller tropical disturbance off the shores of Texas and Tamaulipas, Mexico. (NOAA/National Weather Service image)
Within the last few years, the early-summer emergence of vast waves of mayflies has caused great consternation among residents of riverside towns and motorists who cross the bridges over the lower Susquehanna. Fishermen and others who frequent the river are familiar with the phenomenon. Mayflies rise from their benthic environs where they live for a year or more as an aquatic larval stage (nymph) to take flight as a short-lived adult (imago), having just one night to complete the business of mating before perishing by the following afternoon.
In 2015, an emergence on a massive scale prompted the temporary closure of the mile-long Columbia-Wrightsville bridge while a blizzard-like flight of huge mayflies reduced visibility and caused road conditions to deteriorate to the point of causing accidents. The slimy smelly bodies of dead mayflies, probably millions of them, were removed like snow from the normally busy Lincoln Highway. Since then, to prevent attraction of the breeding insects, lights on the bridge have been shut down from about mid-June through mid-July to cover the ten to fourteen day peak of the flight period of Hexagenia bilineata, sometimes known as the Great Brown Drake, the species that swarms the bridge.
An adult (imago) male Great Brown Drake (Hexagenia bilineata) burrowing mayfly. Adult mayflies are also known as spinners.A sub-adult (based on the translucence of the wings) female burrowing mayfly (Hexagenia species). The sub-adult (subimago or dun) stage lasts less than a day. Normally within 18 hours of leaving the water and beginning flight, it will molt into an adult, ready to breed during its final night of life.
After so many years, why did the swarms of these mayflies suddenly produce the enormous concentrations seen on this particular bridge across the lower Susquehanna? Let’s have a look.
Following the 2015 flight, conservation organizations were quick to point out that the enormous numbers of mayflies were a positive thing—an indicator that the waters of the river were getting cleaner. Generally, assessments of aquatic invertebrate populations are considered to be among the more reliable gauges of stream health. But some caution is in order in this case.
Prior to the occurrence of large flights several years ago, Hexagenia bilineata was not well known among the species in the mayfly communities of the lower Susquehanna and its tributaries. The native range of the species includes the southeastern United States and the Mississippi River watershed. Along segments of the Mississippi, swarms such as occurred at Columbia-Wrightsville in 2015 are an annual event, sometimes showing up on local weather radar images. These flights have been determined to be heaviest along sections of the river with muddy bottoms—the favored habitat of the burrowing Hexagenia bilineata nymph. This preferred substrate can be found widely in the Susquehanna due to siltation, particularly behind dams, and is the exclusive bottom habitat in Lake Clarke just downstream of the Columbia-Wrightsville bridge.
Native mayflies in the Susquehanna and its tributaries generally favor clean water in cobble-bottomed streams. Hexagenia bilineata, on the other hand, appears to have colonized the river (presumably by air) and has found a niche in segments with accumulated silt, the benthic habitats too impaired to support the native taxa formerly found there. Large flights of burrowing mayflies do indicate that the substrate didn’t become severely polluted or eutrophic during the preceding year. And big flights tell us that the Susquehanna ecosystem is, at least in areas with silt bottoms, favorable for colonization by the Great Brown Drake. But large flights of Hexagenia bilineata mayflies don’t necessarily give us an indication of how well the Susquehanna ecosystem is supporting indigenous mayflies and other species of native aquatic life. Only sustained recoveries by populations of the actual native species can tell us that. So, it’s probably prudent to hold off on the celebrations. We’re a long way from cleaning up this river.
In the absence of man-made lighting, male Great Brown Drakes congregate over waterways lit often by moonlight alone. The males hover in position within a swarm, often downwind of an object in the water. As females begin flight and pass through the swarm, they are pursued by the males in the vicinity. The male response is apparently sight motivated—anything moving through their field of view in a straight line will trigger a pursuit. That’s why they’re so pesky, landing on your face whenever you approach them. Mating takes place as males rendezvous with airborne females. The female then drops to the water surface to deposit eggs and later die—if not eaten by a fish first. Males return to the swarm and may mate again and again. They die by the following afternoon. After hatching, the larvae (nymphs) burrow in the silt where they’ll grow for the coming year. Feathery gills allow them to absorb oxygen from water passing through the U-shaped refuge they’ve excavated.
Several factors increase the likelihood of large swarms of Great Brown Drakes at bridges. Location is, of course, a primary factor. Bridges spanning suitable habitat will, as a minimum, experience incidental occurrences of the flying forms of the mayflies that live in the waters below. Any extraordinarily large emergence will certainly envelop the bridge in mayflies. Lights, both fixed and those on motor vehicles, enhance the appearance of movement on a bridge deck, thus attracting hovering swarms of male Hexagenia bilineata and other species from a greater distance, leading to larger concentrations. Concrete walls along the road atop the bridge lure the males to try to hover in a position of refuge behind them, despite the vehicles that disturb the still air each time they pass. The walls also function as the ultimate visual attraction as headlamp beams and shadows cast by moving vehicles are projected onto them over the length of the bridge. Vast numbers of dead, dying, and maimed mayflies tend to accumulate along these walls for this reason.
The absence of illumination from fixed lighting on the deck of the bridge reduces the density of Great Brown Drake swarms. Some communities take mayfly countermeasures one step further. Along the Mississippi, some bridges are fitted with lights on the underside of the deck to attract the mayflies to the area directly over the water, concentrating the breeding mayflies and fishermen alike. The illumination below the bridge is intended to draw mayflies away from light created by headlamps on motor vehicles passing by on the otherwise dark deck above. Lights beneath the bridge also help prevent large numbers of mayflies from being drawn away from the water toward lights around businesses and homes in neighborhoods along the shoreline—where they can become a nuisance.
Lights out on the Columbia-Wrightsville bridge. Dousing the lights to eliminate fixed illumination on bridges is an effective method of reducing the density of Hexagenia bilineata swarms.With the bridge lights darkened, male Great Brown Drakes, their cellophane-like wings illuminated by headlamps to appear as white spots on the road, number in the hundreds instead of hundreds of thousands in swarms on the bridge near the east and west shorelines.Swarms of Great Brown Drake mayflies are still present at the Columbia-Wrightsville bridge, they’re just not concentrated there in enormous numbers. Evidence includes their bodies found in cobwebs along the entire length of the span.The aptly-named Bridge Orb Weaver (Larinioides sclopetarius) constructs webs along the entire length of the Columbia-Wrightsville bridge, and on many of the buildings at both ends. The abundance of victims tangled in silk must overwhelm their appetite, or maybe they actually consume only the smaller insects. They have their choice. Of the Bridge Orb Weaver, Uncle Ty Dyer says, “When you live along the river, it’s your friendly neighborhood spider, man.”The native Eastern Dobsonfly (Corydalus cornutus) is among the reliable indicators of stream quality in the Susquehanna at the Columbia-Wrightsville bridge. Winged adults, which live for about a week, are clumsy fliers attracted to lights. The aquatic larvae are known as hellgrammites, which require clean flowing water over rocky or pebbly substrate to thrive. Two adults were found on the bridge last evening. It would be encouraging to find more. Maybe we’ll stop back to have another look when the lights are back on.
SOURCES
Edsall, Thomas A. 2001. “Burrowing Mayflies (Hexagenia) as Indicators of Ecosystem Health.” Aquatic Ecosystem Health and Management. 43:283-292.
Fremling, Calvin R. 1960. Biology of a Large Mayfly, Hexagenia bilineata (Say), of the Upper Mississippi River. Research Bulletin 482. Agricultural and Home Economics Experiment Station, Iowa State University. Ames, Iowa.
McCafferty, W. P. 1994. “Distributional and Classificatory Supplement to the Burrowing Mayflies (Ephemeroptera: Ephimeroidea) of the United States.” Entomological News. 105:1-13.
Second Mountain Hawk Watch is located on a ridge top along the northern edge of the Fort Indiantown Gap Military Reservation and the southern edge of State Game Lands 211 in Lebanon County, Pennsylvania. The valley on the north side of the ridge, also known as St. Anthony’s Wilderness, is drained to the Susquehanna by Stony Creek. The valley to the south is drained toward the river by Indiantown Run, a tributary of Swatara Creek.
The hawk watch is able to operate at this prime location for observing the autumn migration of birds, butterflies, dragonflies, and bats through the courtesy of the Pennsylvania Game Commission and the Garrison Commander at Fort Indiantown Gap. The Second Mountain Hawk Watch Association is a non-profit organization that staffs the count site daily throughout the season and reports data to the North American Hawk Watch Association (posted daily at hawkcount.org).
Today, Second Mountain Hawk Watch was populated by observers who enjoyed today’s break in the rainy weather with a visit to the lookout to see what birds might be on the move. All were anxiously awaiting a big flight of Broad-winged Hawks, a forest-dwelling Neotropical species that often travels back to its wintering grounds in groups exceeding one hundred birds. Each autumn, many inland hawk watches in the northeast experience at least one day in mid-September with a Broad-winged Hawk count exceeding 1,000 birds. They are an early-season migrant and today’s southeast winds ahead of the remnants of Hurricane Florence (currently in the Carolinas) could push southwest-heading “Broad-wings” out of the Piedmont Province and into the Ridge and Valley Province for a pass by the Second Mountain lookout.
The flight turned out to be steady through the day with over three hundred Broad-winged Hawks sighted. The largest group consisted of several dozen birds. We would hope there are probably many more yet to come after the Florence rains pass through the northeast and out to sea by mid-week. Also seen today were Bald Eagles, Ospreys, American Kestrels, and a migrating Red-headed Woodpecker.
Migrating Broad-winged Hawks circle on a thermal updraft above Second Mountain Hawk Watch to gain altitude before gliding away to the southwest.
Migrating insects included Monarch butterflies, and the three commonest species of migratory dragonflies: Wandering Glider, Black Saddlebags, and Common Green Darner. The Common Green Darners swarmed the lookout by the dozens late in the afternoon and attracted a couple of American Kestrels, which had apparently set down from a day of migration. American Kestrels and Broad-winged Hawks feed upon dragonflies and often migrate in tandem with them for at least a portion of their journey.
Still later, as the last of the Broad-winged Hawks descended from great heights and began passing by just above the trees looking for a place to settle down, a most unwelcome visitor arrived at the lookout. It glided in from the St. Anthony’s Wilderness side of the ridge on showy crimson-red wings, then became nearly indiscernible from gray tree bark when it landed on a limb. It was the dreaded and potentially invasive Spotted Lanternfly (Lycorma delicatula). This large leafhopper is native to Asia and was first discovered in North America in the Oley Valley of eastern Berks County, Pennsylvania in 2014. The larval stage is exceptionally damaging to cultivated grape and orchard crops. It poses a threat to forest trees as well. Despite efforts to contain the species through quarantine and other methods, it’s obviously spreading quickly. Here on the Second Mountain lookout, we know that wind has a huge influence on the movement of birds and insects. The east and southeast winds we’ve experienced for nearly a week may be carrying Spotted Lanternflies well out of their most recent range and into the forests of the Ridge and Valley Province. We do know for certain that the Spotted Lanternfly has found its way into the Lower Susquehanna River Watershed.
This adult Spotted Lanternfly landed in a birch tree behind the observers at the Second Mountain Hawk Watch late this afternoon. It was first recognized by its bright red wings as it glided from treetops on the north side of the lookout.
It’s sprayed with herbicides. It’s mowed and mangled. It’s ground to shreds with noisy weed-trimmers. It’s scorned and maligned. It’s been targeted for elimination by some governments because it’s undesirable and “noxious”. And it has that four letter word in its name which dooms the fate of any plant that possesses it. It’s the Common Milkweed, and it’s the center of activity in our garden at this time of year. Yep, we said milk-WEED.
Now, you need to understand that our garden is small—less than 2,500 square feet. There is no lawn, and there will be no lawn. We’ll have nothing to do with the lawn nonsense. Those of you who know us, know that the lawn, or anything that looks like lawn, are through.
Anyway, most of the plants in the garden are native species. There are trees, numerous shrubs, some water features with aquatic plants, and filling the sunny margins is a mix of native grassland plants including Common Milkweed. The unusually wet growing season in 2018 has been very kind to these plants. They are still very green and lush. And the animals that rely on them are having a banner year. Have a look…
The flowers of the Common Milkweed were exceptionally fragrant this year. At their peak in early June, their hyacinth-or lilac-like aroma was so prevalent, it drifted into our building and overwhelmed the stink of the neighbor’s filthy dumpster that he had placed 12 feet away from our walls (100 feet from his).Common Milkweed attracts a pollinating Greenbottle Fly (Lucilia species). The dumpster attracts the invasive House Fly (Musca domestica), carrier of dysentery, typhoid, and other wonderful diseases. Are you following this? Remember as we proceed, milkweed is “noxious”.Busy Eastern Carpenter Bees (Xylocopa virginica) load up with pollen from the flowers of the Common Milkweed.A Red Milkweed Beetle (Tetraopes tetrophthalmus) munches on a tender fresh Common Milkweed leaf in mid-June.Following the pollination of the flowers, seed pods will begin to grow. We trim these off the plants. The removal of the extra weight allows most of the stems to remain erect through stormy weather. You’ll still get new plants from underground runners. As you may have guessed, we’re trying to keep these plants upright and strong to host Monarch butterfly larvae.
We’ve planted a variety of native grassland species to help support the milkweed structurally and to provide a more complete habitat for Monarch butterflies and other native insects. This year, these plants are exceptionally colorful for late-August due to the abundance of rain. The warm season grasses shown below are the four primary species found in the American tall-grass prairies and elsewhere.
Big Bluestem, a native warm-season grass in flower.Little Bluestem (Schizachyrium scoparium “Fort Indiantown Gap”) in flower. This variety grows on the tank range at the military base where the armored vehicles and prescribed burns substitute for the herd animals and fires of the prairie to prevent succession and allow it to thrive.Partridge Pea can tolerate sandy soil and is a host plant for vagrant Cloudless Sulphur butterflies.Black-eyed Susan (Rudbeckia hirta) is a popular native grassland wildflower.Indiangrass (Sorghastrum nutans) in flower. This and the other native plants shown here are available as seed from Ernst Seed Company in Meadville (PA). They have an unbelievably large selection of indigenous species. You can plant a small plot or acres and acres using really good mixes blended for purposes ranging from reclaiming pipeline right-of-ways and strip mines to naturalizing backyard gardens.A Red Admiral (Vanessa atalanta) butterfly, a migratory species like the Monarch, on Purple Coneflower (Echinacea purpurea). Yes, it is that Echinacea, the same one used as a supplement and home remedy.
There was Monarch activity in the garden today like we’ve never seen before—and it revolved around milkweed and the companion plants.
A female Monarch laying eggs on a Common Milkweed leaf.A third instar Monarch caterpillar with Oleander Aphids (Aphis nerii) on a Common Milkweed leaf. Both of these insect species absorb toxins from the milkweed which makes them distasteful to predators.Fifth instar (left and center) and fourth instar (right) monarch caterpillars devour a Common Milkweed leaf. There were over thirty of these caterpillars in just a ten by ten feet area this morning. We hope that if you’re keeping a habitat for Monarchs, you’re enjoying the same fortune right now!A slow-moving Monarch stopped for a break after making the circuit to deposit eggs on milkweed throughout the garden.Third instar (top), fourth instar (right), and fifth instar (left) Monarch caterpillars quickly consume the leaf of a Common Milkweed plant. Caterpillars emerging from eggs deposited today may not have sufficient late-season food to complete the larval segment of their life cycle. Need more milkweed!After benefiting from the nourishment of the Common Milkweed plant, a fifth instar Monarch caterpillar begins pupation on Big Bluestem grass.Two hours later, the chrysalis is complete.Another chrysalis, this one on flowering Switchgrass just two feet away from the previous one. An adult Monarch will emerge from this pupa to become part of what we hope will be the most populated southbound exodus for the species in over five years.There it is, soon ready to fly away. And all courtesy of the noxious milkweed.A chrysalis can often be found on man-made objects too. This one is on the rim of a flower pot.Ornamental flowers can attract adult Monarch butterflies seeking nectar. We’re now more careful to select seeds and plants that have not been treated with neonicotinoid insecticides. There’s growing concern over the impact these compounds may be having on pollinating species of animals. Oh…and we don’t mow, whack, cut, mutilate, or spray herbicides on our milkweed, but you probably figured that out already.
SOURCES
Eaton, Eric R., and Kenn Kaufman. 2007. Kaufman Field Guide to Insects of North America. Houghton Mifflin Company. New York.
It’s been an atypical summer. The lower Susquehanna River valley has been in a cycle of heavy rains for over a month and stream flooding has been a recurring event. At Conewago Falls, the Pothole Rocks have been inundated for weeks. The location used as a lookout for the Autumn Migration Count last fall is at the moment submerged in ten feet of roaring water. Any attempt to tally the migrants which are passing thru in 2018 will thus be delayed indefinitely. Of greater import, the flooding at Conewago Falls is impacting many of the animals and plants there at a critical time in their annual life cycle. Having been displaced from its usual breeding sites on the river, one insect species in particular seems to be omnipresent in upland areas right now, and few people have ever heard of it.
So, you take a cruise in the motorcar to your favorite store and arrive at the sprawling parking lot. Not wishing to have your doors dented or paint chipped because you settled for a space tightly packed among other shopper’s conveyances, you park out there in the “boondocks”. You know the place, the lightly-used portion of the lot where sometimes brush grows from cracks in the asphalt and you must be on alert for impatient consumers who throttle-up to high speeds and dash diagonally across the carefully painted grids on the pavement to reach their favorite parking destination in the front row. Coming to a stop, you take the car out of gear, set the brake, disengage the safety belt, and gather your shopping list. You grasp the door handle and, not wanting to be flattened by one of the aforementioned motorists, you have a look around before exiting.
It was then that you saw the thing, hovering above your shiny bright hood. For a brief moment, it seemed to be peering right through the windshield at you with big reddish-brown eyes. In just a second or two, it turned its whole bronze body ninety degrees to the left and darted away on its cellophane wings. Maybe you didn’t really get a good look at it. It was so fast. But it certainly was odd. Oh well, time to walk inside a grab a few provisions. Away you go.
Upon completion of your shopping, you’re taking the long stroll back to your car and you notice more of these peculiar creatures. Two are coupled together and are hovering above someone’s automobile hood, then they drop down, and the lower of the two taps its abdomen on the paint. You ask yourself, “What are these bizarre things?”
Meet the Wandering Glider (Pantala flavescens), also known as the Globe Wanderer or Globe Skimmer, a wide-ranging dragonfly known to occur on every continent with the exception of Antarctica.
Wandering Gliders sometimes arrive in the lower Susquehanna River valley in large numbers after catching a ride on sustained winds from southerly directions and will often fly and migrate in storm systems. Conditions for such movements have been optimal in our region since mid-July. These dragonflies will often hover above motor vehicle hoods and, after mating, females will deposit eggs upon them, apparently mistaking their glossy surface for small pools of water.
Wandering Gliders travel the globe, and as such are accomplished fliers. Adults spend most of the day on the wing, feeding upon a variety of flying insects. Days ago, I watched several intercepting a swarm of flying ants. As fast as ants left the ground they were grabbed and devoured by the gliders. Wandering Gliders are adept at taking day-flying mosquitos, often zipping stealthily past a person’s head or shoulders to grab one of the little pests—the would-be skeeter victim usually unaware of the whole affair.
Due to their nomadic life history, Wandering Gliders are opportunists when breeding and will lay eggs in most any body of freshwater. Their larvae do not overwinter prior to maturity; adults can be expected in a little more than one to two months. Repetitive flooding in the Lower Susquehanna River Watershed this summer may be reducing the availability of the best local breeding sites for this species—riverine, stream, and floodplain pools of standing water with prey. This may explain why thousands of Wandering Gliders are patrolling parking lots, farmlands, and urban areas this summer. And it’s the likely reason for their use of puddles on asphalt pavement, on rubber roofs, and in fields as places to try to deposit eggs. Unfortunately, they may be as likely to succeed there as they are on your motor vehicle hood.
At this time a year ago, the airspace above the Diabase Pothole Rocks at Conewago Falls was jammed with territorial male Wandering Gliders. Each male hovered at various locations around his breeding territory consisting of pools and water-filled potholes. Intruders would quickly be dispatched from the area, then the male would resume his patrols from a set of repetitively-used hovering positions about six feet above the rocks. Mating and egg-laying continued into late September. The larvae, also called nymphs or naiads, were readily observed in many pools and potholes in early October and the emergence of juveniles was noted in mid-October. The absence of flooding, the mild autumn weather, and the moderation of water temperatures in the pools and potholes courtesy of the sun-drenched diabase boulders helped to extend the 2017 breeding season for Wandering Gliders in Conewago Falls. They aren’t likely to experience the same favor this year, but their great ability to travel and adapt should overcome this momentary misfortune.
A male Wandering Glider aggressively patrols his territory in the Diabase Pothole Rocks Microhabitat at Conewago Falls. August 20, 2017.A mating pair of Wandering Gliders continue flying non-stop above one of thousands of suitable breeding pools among the Diabase Pothole Rocks at Conewago Falls. September 23, 2017.A female (bottom)Wandering Glider has deposited eggs in a pool while flying in tandem with a male (top). They’ll do the same thing on your automobile hood! Conewago Falls Diabase Pothole Rocks Microhabitat. September 23, 2017.Wandering Glider larvae are at the top of the food chain in flooded potholes. As they grew, these dragonfly larvae decimated the mosquito larvae which were abundant there earlier in the summer. October 7, 2017.A juvenile male Wandering Glider emerges from the pool where it fed and grew as a larva. It remained at water’s edge on the surface of a sun-warmed diabase rock for several hours to dry its wings. It soon flew away to parts unknown, possibly traveling hundreds or thousands of miles. Look carefully at the wings for the beige dash marks on the forward edge near the terminal end. Females lack this marking. Conewago Falls Diabase Pothole Rocks Microhabitat. October 14, 2017.A Wandering Glider exuviae, the shed exoskeleton of a creature gone, but not forgotten. October 14, 2017.
There are two Conewago Creek systems in the Lower Susquehanna River Watershed. One drains the Gettysburg Basin west of the river, mostly in Adams and York Counties, then flows into the Susquehanna at the base of Conewago Falls. The other drains the Gettysburg Basin east of the river, flowing through Triassic redbeds of the Gettysburg Formation and York Haven Diabase before entering Conewago Falls near the south tip of Three Mile Island. Both Conewago Creeks flow through suburbia, farm, and forest. Both have their capacity to support aquatic life impaired and diminished by nutrient and sediment pollution.
This week, some of the many partners engaged in a long-term collaboration to restore the east shore’s Conewago Creek met to have a look at one of the prime indicators of overall stream habitat health—the fishes. Kristen Kyler of the Lower Susquehanna Initiative organized the effort. Portable backpack-mounted electrofishing units and nets were used by crews to capture, identify, and count the native and non-native fishes at sampling locations which have remained constant since prior to the numerous stream improvement projects which began more than ten years ago. Some of the present-day sample sites were first used following Hurricane Agnes in 1972 by Stambaugh and Denoncourt and pre-date any implementation of sediment and nutrient mitigation practices like cover crops, no-till farming, field terracing, stormwater control, nutrient management, wetland restoration, streambank fencing, renewed forested stream buffers, or modernized wastewater treatment plants. By comparing more recent surveys with this baseline data, it may be possible to discern trends in fish populations resulting not only from conservation practices, but from many other variables which may impact the Conewago Creek Warmwater Stream ecosystem in Dauphin, Lancaster, and Lebanon Counties.
So here they are. Enjoy these shocking fish photos.
Matt Kofroth, Watershed Specialist with the Lancaster County Conservation District, operates the electrofishing wand in Conewago Creek while his team members prepare to net and collect momentarily-stunned fish. Three other electrofishing units operated by staff from the Susquehanna River Basin Commission and aided by teams of netters were in action at other sample locations along the Conewago on this day.Really big fish, such as this Common Carp (Cyprinus carpio), were identified, counted, and immediately returned to the water downstream of the advancing electrofishing team. Koi of the garden pond are a familiar variety of Common Carp, a native of Asia.Other fish, such as the Swallowtail Shiner, Redbreast Sunfish (Lepomis auritus), Fallfish, and suckers seen here, were placed in a sorting tank.Fallfish (Semotilus corporalis) are very active and require plenty of dissolved oxygen in the water to survive. Fallfish, Rainbow Trout (Oncorhynchus mykiss), and Smallmouth Bass (Micropterus dolomieu) were quickly identified and removed from the sorting tank for release back into the stream. Other larger, but less active fish, including suckers, quickly followed.Small fish like minnows were removed from the sorting tank for a closer look in a hand-held viewing tank. This Fathead Minnow (Pimephales promelas) was identified, added to the tally sheet, and released back into the Conewago. The Fathead Minnow is not native to the Susquehanna drainage. It is the minnow most frequently sold as bait by vendors.A breeding condition male Bluntnose Minnow (Pimephales notatus).The Cutlips Minnow (Exoglossum maxillingua) is a resident of clear rocky streams. Of the more than 30 species collected during the day, two native species which are classified as intolerant of persisting stream impairment were found: Cutlips Minnow and Swallowtail Shiner.This young River Chub (Nocomis micropogon) is losing its side stripe. It will be at least twice as large at adulthood.The Eastern Blacknose Dace (Rhinichthys atratulus) is found in clear water over pebble and stone substrate..The Longnose Dace (Rhinichthys cataractae) is another species of pebbly rocky streams.A juvenile Golden Shiner (Notemigonus crysoleucas). Adults lack the side stripe and grow to the size of a sunfish.A Swallowtail Shiner (Notropis procne) and a very young White Sucker (Catostomus commersonii) in the upper left of the tank.A Spotfin Shiner (Cyprinella spiloptera).A breeding male Spotfin Shiner. Show-off!The Margined Madtom (Noturus insignis) is a small native catfish of pebbly streams.The Banded Killifish (Fundulus diaphanus) is adept at feeding upon insects, including mosquitos.A young Rock Bass (Ambloplites rupestris). This species was introduced to the Susquehanna and its tributaries.The Greenside Darter (Etheostoma blennioides) is not native to the Susquehanna basin. The species colonized the Conewago Creek (east) from introduced local populations within the last five years.The Tessellated Darter (Etheostoma olmstedi) is a native inhabitant of the Susquehanna and its tributaries.The stars of the day were the American Eels (Anguilla rostrata).After collection, each eel was measured and weighed using a scale and dry bucket. This specimen checked in at 20 inches and one pound before being released.Prior to the construction of large dams, American Eels were plentiful in the Susquehanna and its tributaries, including the Conewago. They’ve since been rarities for more than half a century. Now they’re getting a lift.American Eels serve as an intermediate host for the microscopic parasitic glochidia (larvae) of the Eastern Elliptio (Elliptio complanata), a declining native freshwater mussel of the Lower Susquehanna River Watershed. While feeding on their host (usually in its gills), the glochidia cause little injury and soon drop off to continue growth, often having assured distribution of their species by accepting the free ride. Freshwater mussels are filter feeders and improve water quality. They grow slowly and can live for decades.American Eels are a catadromous species, starting life as tiny glass eels in the saltwater of the Atlantic Ocean, then migrating to tidal brackish marshes and streams (males) or freshwater streams (females) to mature. This 20-incher probably attempted to ascend the Susquehanna as an elver in 2016 or 2017. After hitching a ride with some friendly folks, she bypassed the three largest dams on the lower Susquehanna (Conowingo, Holtwood, and Safe Harbor) and arrived in the Conewago where she may remain and grow for ten years or more. To spawn, a perilous and terminally fatal journey to the Sargasso Sea awaits her. (You may better know the area of the Sargasso Sea as The Bermuda Triangle…a perilous place to travel indeed!)
SOURCES
Normandeau Associates, Inc. and Gomez and Sullivan. 2018. Muddy Run Pumped Storage Project Conowingo Eel Collection Facility FERC Project 2355. Prepared for Exelon.
Stambaugh, Jr., John W., and Robert P. Denoncourt. 1974. A Preliminary Report on the Conewago Creek Faunal Survey, Lancaster County, Pennsylvania. Proceedings of the Pennsylvania Academy of Sciences. 48: 55-60.
The NOAA National Weather Service radar images from last evening provided an indication that there may be a good fallout of birds at daybreak in the lower Susquehanna valley. The moon was bright, nearly full, and there was a gentle breeze from the north to move the nocturnal migrants along. The conditions were ideal.
Rising from daytime roosts in New York and Pennsylvania, then streaming south in moonlit skies, migrating birds are recorded as echoes on this post-sunset composite NEXRAD loop from last evening. (NOAA/National Weather Service image)
The Riparian Woodlands at Conewago Falls were alive with migrants this morning. American Robins and White-throated Sparrows were joined by new arrivals for the season: Brown Creeper (Certhia americana), Ruby-crowned Kinglets (Regulus calendula), Golden-crowned Kinglets (Regulus satrapa), Dark-eyed Junco (Junco hyemalis), and Yellow-rumped Warbler (Setophaga coronata). These are the perching birds one would expect to have comprised the overnight flight. While the individuals that will remain may not yet be among them, these are the species we will see wintering in the Mid-Atlantic states. No trip to the tropics for these hardy passerines.
American Robins continued migratory flight into the first hour of daylight this morning. Their calls are commonly heard at night as migrating individuals pass overhead.White-throated Sparrows are nocturnal migrants, and are a familiar find on woodland edges and at suburban feeding stations through the winter.Dark-eyed Juncos, also nocturnal migrants, are common winter residents in the Lower Susquehanna River Watershed, frequently visiting bird feeders.Heavy rain earlier this week in the Susquehanna River drainage basin has flooded most of the Pothole Rocks; the rapids of Conewago Falls have returned.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
It was a placid morning on Conewago Falls with blue skies dotted every now and then by a small flock of migrating robins or blackbirds. The jumbled notes of a singing Winter Wren (Troglodytes hiemalis) in the Riparian Woodland softly mixed with the sounds of water spilling over the dam. The season’s first Wood Ducks (Aix sponsa), Blue-winged Teal (Spatula discors), Herring Gull (Larus argentatus), Horned Larks (Eremophila alpestris), and White-throated Sparrows (Zonotrichia albicollis) were seen.
There was a small ruckus when one of the adult Bald Eagles from a local pair spotted an Osprey passing through carrying a fish. This eagle’s effort to steal the Osprey’s catch was soon interrupted when an adult eagle from a second pair that has been lingering in the area joined the pursuit. Two eagles are certainly better than one when it’s time to hustle a skinny little Osprey, don’t you think?
But you see, this just won’t do. It’s a breach of eagle etiquette, don’t you know? Soon both pairs of adult eagles were engaged in a noisy dogfight. It was fussing and cackling and the four eagles going in every direction overhead. Things calmed down after about five minutes, then a staring match commenced on the crest of the dam with the two pairs of eagles, the “home team” and the “visiting team”, perched about 100 feet from each other. Soon the pair which seems to be visiting gave up and moved out of the falls for the remainder of the day. The Osprey, in the meantime, was able to slip away.
In recent weeks, the “home team” pair of Bald Eagles, seen regularly defending territory at Conewago Falls, has been hanging sticks and branched tree limbs on the cross members of the power line tower where they often perch. They seem only to collect and display these would-be nest materials when the “visiting team” pair is perched in the nearby tower just several hundred yards away…an attempt to intimidate by homesteading. It appears that with winter and breeding time approaching, territorial behavior is on the increase.
The second migrating Osprey of the day ran the gauntlet of marauding eagles without incident.
In the afternoon, a fresh breeze from the south sent ripples across the waters among the Pothole Rocks. The updraft on the south face of the diabase ridge on the east shore was like a highway for some migrating hawks, falcons, and vultures. Black Vultures (Coragyps atratus) and Turkey Vultures streamed off to the south headlong into the wind after leaving the ridge and crossing the river. A male and female Northern Harrier (Circus hudsonius), ten Red-tailed Hawks, two Red-shouldered Hawks (Buteo lineatus), six Sharp-shinned Hawks, and two Merlins crossed the river and continued along the diabase ridge on the west shore, accessing a strong updraft along its slope to propel their journey further to the southwest. Four high-flying Bald Eagles migrated through, each following the east river shore downstream and making little use of the ridge except to gain a little altitude while passing by.
(Top and Middle) Turkey Vultures riding the fresh breeze and teetering to-and-fro on up-tilted wings. This wing posture is known as a dihedral. (Bottom) More than 100 migrating Black Vultures climbed high on the afternoon breeze to make an oblique crossing of the river and maintain a southbound course.
Late in the afternoon, the local Bald Eagles were again airborne and cackling up a storm. This time they intercepted an eagle coming down the ridge toward the river and immediately forced the bird to climb if it intended to pass. It turned out to be the best sighting of the day, and these “home team” eagles found it first. It was a Golden Eagle (Aquila chrysaetos) in crisp juvenile plumage. On its first southward voyage, it seemed to linger after climbing high enough for the Bald Eagles to loose concern, then finally selected the ridge route and crossed the river to head off to the southwest.
Ring-billed Gulls began feeding during the afternoon as clouds preceding stormy weather approached.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
The humid rainy remains of Hurricane Nate have long since passed by Pennsylvania, yet mild wet weather lingers to confuse one’s sense of the seasons. This gloomy misty day was less than spectacular for watching migrating birds and insects, but some did pass by. Many resident animals of the falls are availing themselves of the opportunity to continue active behavior before the cold winds of autumn and winter force a change of lifestyle.
Warm drizzle at daybreak prompted several Northern Spring Peepers (Pseudacris crucifer crucifer) to begin calling from the wetlands in the Riparian Woodlands of Conewago Falls. An enormous chorus of these calls normally begins with the first warm rains of early spring to usher in this tiny frog’s mating season. Today, it was just a few “peeps” among anxious friends.
The tiny Northern Spring Peeper is recognized by the dark “X” across its back. Soon, shelter must be found among loose bark and fallen logs to commence hibernation. Emergence, often prompted by warm spring rains, will quickly be followed by a growing chorus of breeding calls as sometimes hundreds of these frogs assemble in vernal pools where mating will then occur.
Any additional river flow that resulted from the rains of the previous week is scarcely noticeable among the Pothole Rocks. The water level remains low, the water column is fairly clear, and the water temperatures are in the 60s Fahrenheit.
It’s no real surprise then to see aquatic turtles climbing onto the boulders in the falls to enjoy a little warmth, if not from the sun, then from the stored heat in the rocks. As usual, they’re quick to slide into the depths soon after sensing someone approaching or moving nearby. Seldom found anywhere but on the river, these skilled divers are Common Map Turtles (Graptemys geographica), also known as Northern Map Turtles. Their paddle-like feet are well adapted to swimming in strong current. They are benthic feeders, feasting upon a wide variety of invertebrates found among the stone and substrate of the river bottom.
Adult Common Map Turtles hibernate communally on the river bottom in a location protected from ice scour and turbulent flow, often using boulders, logs, or other structures as shelter from strong current. The oxygenation of waters tumbling through Conewago Falls may be critical to the survival of the turtles overwintering downstream. Dissolved oxygen in the water is absorbed by the nearly inactive turtles as they remain submerged at their hideout through the winter. Though Common Map Turtles, particularly males, may occasionally move about in their hibernation location, they are not seen coming to the surface to breathe.
The Common Map Turtles in the Susquehanna River basin are a population disconnected from that found in the main range of the species in the Great Lakes and upper Mississippi basin. Another isolated population exists in the Delaware River.
Common Map Turtles, including this recently hatched young seen in August, are often observed climbing onto rocks in the river.Note the oversize swimming fin adaptations of the feet on this adult Common Map Turtle found among the Pothole Rocks in Conewago Falls. Young and adults are capable of navigating some strong current to feed and escape danger.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
SOURCES
Committee on the Status of Endangered Wildlife in Canada. 2002. Status Report of the Northern Map Turtle. Canadian Wildlife Service. Ottawa, Ontario.
A moderate breeze from the south placed a headwind into the face of migrants trying to wing their way to winter quarters. The urge to reach their destination overwhelmed any inclination a bird or insect may have had to stay put and try again another day.
Blue Jays were joined by increasing numbers of American Robins crossing the river in small groups to continue their migratory voyages. Killdeer (Charadrius vociferous) and a handful of sandpipers headed down the river route. Other migrants today included a Cooper’s Hawk (Accipiter cooperii), Eastern Bluebirds (Sialia sialis), and a few Common Mergansers (Mergus merganser), House Finches (Haemorhous mexicanus), and Common Grackles (Quiscalus quiscula).
The afternoon belonged to the insects. The warm wind blew scores of Monarchs toward the north as they persistently flapped on a southwest heading. Many may have actually lost ground today. Painted Lady (Vanessa cardui) and Cloudless Sulphur butterflies were observed battling their way south as well. All three of the common migrating dragonflies were seen: Common Green Darner (Anax junius), Wandering Glider (Pantala flavescens), and Black Saddlebags (Tramea lacerata).
The warm weather and summer breeze are expected to continue as the rain and wind from Hurricane Nate, today striking coastal Alabama and Mississippi, progresses toward the Susquehanna River watershed during the coming forty-eight hours.
This Great Blue Heron was joined by numerous other fishermen and a good number of sightseers in the falls today.A colorful young Northern Water Snake (Nerodia sipedon) takes advantage of the sun-heated surface of a Pothole Rock to remain nimble and active. Cooler weather will soon compel this and other reptiles to find shelter for winter hibernation.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
A fresh breeze from the north brought cooler air and a reminder that summer is gone and autumn has arrived.
Fast-moving dark clouds provided a perfect backdrop for viewing passing diurnal migrants. Bald Eagles utilized the tail wind to cruise down the Susquehanna toward Chesapeake Bay and points further south. A migrating Merlin began a chase from which a Northern Flicker narrowly escaped by finding shelter among Pothole Rocks and a few small trees. The season’s first American Black Duck (Anas rubripes), Common Loon (Gavia immer), Yellow-bellied Sapsucker (Sphyrapicus varia), and American Pipits (Anthus rubescens) moved through.
Blue Jays continued their hesitant crossings of the river at Conewago Falls. The majority completed the journey by forming groups of a dozen or more birds and following the lead of a lone American Robin, a Northern Flicker, or, odd as it appeared, a small warbler.
By far the most numerous migrants today were swallows. Thousands of Northern Rough-winged Swallows and hundreds of Tree Swallows were on the wing in search of what was suddenly a sparse flying insect supply. To get out of the brisk wind, some of the more resourceful birds landed on the warm rocks. To satisfy their appetite, many were able to pick crawling arthropods from the surface of the boulders. They swallow them whole.
A few of the thousands of swallows seen at Conewago Falls today.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
The Neotropical birds that raised their young in Canada and in the northern United States have now logged many miles on their journey to warmer climates for the coming winter. As their density decreases among the masses of migrating birds, a shift to species with a tolerance for the cooler winter weather of the temperate regions will be evident.
Though it is unusually warm for this late in September, the movement of diurnal migrants continues. This morning at Conewago Falls, five Broad-winged Hawks (Buteo platypterus) lifted from the forested hills to the east, then crossed the river to continue a excursion to the southwest which will eventually lead them and thousands of others that passed through Pennsylvania this week to wintering habitat in South America. Broad-winged Hawks often gather in large migrating groups which swarm in the rising air of thermal updrafts, then, after gaining substantial altitude, glide away to continue their trip. These ever-growing assemblages from all over eastern North America funnel into coastal Texas where they make a turn to south around the Gulf of Mexico, then continue on toward the tropics. In the coming weeks, a migration count at Corpus Christi in Texas could tally 100,000 or more Broad-winged Hawks in a single day as a large portion of the continental population passes by. You can track their movement and that of other diurnal raptors as recorded at sites located all over North America by visiting hawkcount.org on the internet. Check it out. You’ll be glad you did.
Nearly all of the other migrants seen today have a much shorter flight ahead of them. Red-bellied Woodpeckers (Melanerpes carolinus), Red-headed Woodpeckers (Melanerpes erythrocephalus), and Northern Flickers (Colaptes auratus) were on the move. Migrating American Robins (Turdus migratorius) crossed the river early in the day, possibly leftovers from an overnight flight of this primarily nocturnal migrant. The season’s first Great Black-backed Gulls (Larus marinus) arrived. American Goldfinches are easily detected by their calls as they pass overhead. Look carefully at the goldfinches visiting your feeder, the birds of summer are probably gone and are being replaced by migrants currently passing through.
By far, the most conspicuous migrant today was the Blue Jay. Hundreds were seen as they filtered out of the hardwood forests of the diabase ridge to cautiously cross the river and continue to the southwest. Groups of five to fifty birds would noisily congregate in trees along the river’s edge, then begin flying across the falls. Many wary jays abandoned their small crossing parties and turned back. Soon, they would try the trip again in a larger flock.
Sensing that they are being watched, Blue Jays are hesitant to fly across the narrow Susquehanna at Conewago Falls without first assembling into a flock. The local constabulary often penalizes those who freelance and do not move in orderly groups.
A look at this morning’s count reveals few Neotropical migrants. With the exception of the Broad-winged Hawks and warblers, the migratory species seen today will winter in a sub-tropical temperate climate, primarily in the southern United States, but often as far north as the lower Susquehanna River valley. The individual birds observed today will mostly continue to a winter home a bit further south. Those that will winter in the area of Conewago Falls will arrive in October and later.
The Great Blue Heron (Ardea herodius) can be found year-round at Conewago Falls, provided there is open water and adequate food. Migrants from breeding colonies to the north will soon supplement the local population.The Double-crested Cormorant (Phalacrocorax auritus) is a summer resident at Conewago Falls. Migration of the local population and of those from further north will soon begin. All will be gone by the time ice forms on the river. Cormorants are often seen drying their feathers in sunlight following a series of feeding dives.
The long-distance migrating insect so beloved among butterfly enthusiasts shows signs of improving numbers. Today, more than two dozen Monarchs were seen crossing the falls and slowly flapping and gliding their way to Mexico.
CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
They get a touch of it here, and a sparkle or two there. Maybe, for a couple of hours each day, the glorious life-giving glow of the sun finds an opening in the canopy to warm and nourish their leaves, then the rays of light creep away across the forest floor, and it’s shade for the remainder of the day.
The flowering plants which thrive in the understory of the Riparian Woodlands often escape much notice. They gather only a fraction of the daylight collected by species growing in full exposure to the sun. Yet, by season’s end, many produce showy flowers or nourishing fruits of great import to wildlife. While light may be sparingly rationed through the leaves of the tall trees overhead, moisture is nearly always assured in the damp soils of the riverside forest. For these plants, growth is slow, but continuous. And now, it’s show time.
So let’s take a late-summer stroll through the Riparian Woodlands of Conewago Falls, minus the face full of cobwebs, and have a look at some of the strikingly beautiful plants found living in the shadows.
Oxeye (Heliopsis helianthoides) is common on the interior and along the edges of Riparian Woodland. Specimens in deep shade flower less profusely and average less than half the height of the five feet tall inhabitants of edge environs.Pale Touch-Me-Not (Impatiens pallida) is one of two species of native Impatiens foundin the river floodplain. Both are known as Jewelweed. The stems and leaves of the indigenous Impatiens retain a great quantity of water, so life in filtered sunlight is essential to prevent desiccation. Contrary to popular folklore, extracts of Jewelweed plants are not effective treatments of Poison Ivy (Toxicodendron radicans) contact dermatitis.Spotted Touch-Me-Not (Impatiens capensis) is typically found in wetter soil than I. pallida. Both Jewelweeds develop popping capsules which help to distribute the seeds of these annual wildflowers. “Touch Me Not”, or you’ll be wearing tiny seeds.Green-headed Coneflower (Rudbeckia laciniata) grows to heights of eight feet in full sun, hence its alternate common name, Tall Coneflower. In deep shade, it may not exceed two feet in height. Floodplains are the prime domain of this perennial.Wingstem (Verbesina alternifolia) normally flowers no earlier than late August. The bases of the leaves are continued onto the stem of the plant to form wings which extend downward along its length. This wildflower tolerates shade, but flowers more profusely along the woodland edge.Great Lobelia (Lobelia siphilitica), or Great Blue Lobelia, is a magnificent wetland and moist woodland wildflower, usually attaining three feet in height and adorned with a plant-topping spike of blossoms. Invasive Japanese Stiltgrass (Microstegium vimineum) can be seen here competing with this plant, resulting in a shorter, less productive Lobelia. Stiltgrass was not found in the Susquehanna River floodplain at Conewago Falls until sometime after 1997. It has spread to all areas of woodland shade, its tiny seeds being blown and translocated along roads, mowed lots, trails, and streams to quickly colonize and overtake new ground.American Bladdernut (Staphylea trifolia), a shrub of shaded woods, develops inflated capsules which easily float away during high water to distribute the seeds contained inside.Buttonbush (Cephalanthus occidentalis) is a shrub of wet soils which produces a strange spherical flower, followed by this globular seed cluster.Common Pawpaw (Asimina triloba) is a colony-forming small tree which produces a fleshy fruit. It is the host plant for the caterpillars of the Zebra Swallowtail. The plant and the butterfly approach the northern limit of their geographic range at Conewago Falls.Common Spicebush (Lindera benzoin) is a widespread understory shrub in wet floodplain soils. It is the host plant for the caterpillars of the Spicebush Swallowtail (Papilio troilus).Sweet Autumn Virgin’s Bower (Clematis terniflora) is an escape from cultivation which has recently naturalized in the edge areas of the Conewago Falls Riparian Woodlands. This vine is very showy when flowering and producing seed, but can be detrimental to some of the understory shrubs upon which it tends to climb.
SOURCES
Long, David; Ballentine, Noel H.; and Marks, James G., Jr. 1997. Treatment of Poison Ivy/Oak Allergic Contact Dermatitis With an Extract of Jewelweed. American Journal of Contact Dermatitis. 8(3): pp. 150-153.
Newcomb, Lawrence. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. Boston, Massachusetts.
A few nocturnal migrants flew through the moonlit night to arrive at Conewago Falls for a sunrise showing this morning. A dozen warblers were in the treetops and a Wood Thrush (Hylocichla mustelina) chattered away in the understory of the Riparian Woodlands. Three species of shorebirds were in the falls and on the Pothole Rocks: Least Sandpiper (Calidris minutilla), Lesser Yellowlegs (Tringa flavipes), and Greater Yellowlegs (Tringa melanoleuca).
A Greater Yellowlegs (right) and two Lesser Yellowlegs sandpipers dropped by for breakfast.
The diurnal migration was highlighted by a Merlin (Falco columbarius), an Osprey, and a Bald Eagle, each flying down the river. Most of the other birds in the falls seemed content to linger and feed. There’s no need to hurry folks, only trouble lurks down there in paradise at the moment.
A light to moderate flight of nocturnal migrants in the eastern United States is displayed on NOAA National Weather Service NEXRAD radar at 4:58 AM EDT. The eye of Hurricane Irma can be seen approaching the Florida Keys. (NOAA/National Weather Service image)CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
A couple of inches of rain this week caused a small increase in the flow of the river, just a burp, nothing major. This higher water coincided with some breezy days that kicked up some chop on the open waters of the Susquehanna upstream of Conewago Falls. Apparently it was just enough turbulence to uproot some aquatic plants and send them floating into the falls.
Piled against and upon the upstream side of many of the Pothole Rocks were thousands of two to three feet-long flat ribbon-like opaque green leaves of Tapegrass, also called Wild Celery, but better known as American Eelgrass (Vallisneria americana). Some leaves were still attached to a short set of clustered roots. It appears that most of the plants broke free from creeping rootstock along the edge of one of this species’ spreading masses which happened to thrive during the second half of the summer. You’ll recall that persistent high water through much of the growing season kept aquatic plants beneath a blanket of muddy current. The American Eelgrass colonies from which these specimens originated must have grown vigorously during the favorable conditions in the month of August. A few plants bore the long thread-like pistillate flower stems with a fruit cluster still intact. During the recent few weeks, there have been mats of American Eelgrass visible, the tops of their leaves floating on the shallow river surface, near the east and west shorelines of the Susquehanna where it begins its pass through the Gettysburg Basin near the Pennsylvania Turnpike bridge at Highspire. This location is a probable source of the plants found in the falls today.
Uprooted American Eelgrass floating into the Pothole Rocks under the power of a north wind. Note the white thread-like pistillate flower stem to the left and the small rooted specimen to the upper right. The latter is likely a plant from the creeping rootstock on the edge of a colony. As a native aquatic species, American Eelgrass is a critical link in the Susquehanna River and Chesapeake Bay food chain. Its decimation by pollution during the twentieth century led to migration pattern alterations and severe population losses for the Canvasback (Aythya valisineria) duck.American Eelgrass, a very small specimen, found growing in a low-lying Pothole Rock alongside the accumulations of freshly arriving material from upstream. Note that the creeping rootstock has leaves growing from at least three nodes on this plant. Eelgrass dislocations are regular occurrences which sometimes begin new colonies, like the small one seen here in this Diabase Pothole Rock Microhabitat.
The cool breeze from the north was a perfect fit for today’s migration count. Nocturnal migrants settling down for the day in the Riparian Woodlands at sunrise included more than a dozen warblers and some Gray Catbirds (Dumetella carolinensis). Diurnal migration was underway shortly thereafter.
A moderate flight of nocturnal migrants is indicated around NEXRAD sites in the northeastern states at 3:18 AM EDT. The outer rain bands of Hurricane Irma can be seen approaching the Florida Keys as the storm closes in on the peninsula. (NOAA/National Weather Service image)
Four Bald Eagles were counted as migrants this morning. Based on plumage, two were first-year eagles (Juvenile) seen up high and flying the river downstream, one was a second-year bird (Basic I) with a jagged-looking wing molt, and a third was probably a fourth year (Basic III) eagle looking much like an adult with the exception of a black terminal band on the tail. These birds were the only ones which could safely be differentiated from the seven or more Bald Eagles of varying ages found within the past few weeks to be lingering at Conewago Falls. There were as many as a dozen eagles which appeared to be moving through the falls area that may have been migrating, but the four counted were the only ones readily separable from the locals.
Red-tailed Hawks (Buteo jamaicensis) were observed riding the wind to journey not on a course following the river, but flying across it and riding the updraft on the York Haven Diabase ridge from northeast to southwest.
Bank Swallows (Riparia riparia) seem to have moved on. None were discovered among the swarms of other species today.
Ruby-throated Hummingbirds, Caspian Terns, Cedar Waxwings (Bombycilla cedrorum), and Chimney Swifts (Chaetura pelagica) were migrating today, as were Monarch butterflies.
Not migrating, but always fun to have around, all four wise guys were here today. I’m referring to the four members of the Corvid family regularly found in the Mid-Atlantic states: Blue Jay (Cyanocitta cristata), American Crow (Corvus brachyrhynchos), Fish Crow (Corvus ossifragus), and Common Raven (Corvus corax).
It looks like a big Blue Jay, but it’s not. This Belted Kingfisher (Megaceryle alcyon) takes a break after flying around the falls trying to shake a marauding Ruby-throated Hummingbird off its tail.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
SOURCES
Klots, Elsie B. 1966. The New Field Book of Freshwater Life. G. P. Putnam’s Sons. New York, NY.
A Baltimore Oriole (Icterus galbula) glowed in the first sunlight of the day as it began illuminating the treetops. I’m not certain of the cause, but I often have the urge to dig into a bowl of orange sherbet after seeing one these magnificent blackbirds. That’s right, in the Americas, orioles and blackbirds are members of the same family, Icteridae. Look at blackbirds more carefully, you might see the resemblance.
Sunshine at dawn and migrating warblers were again active in the foliage. Eight species were identified today. Off to the tropics they go. To the land of palm and citrus, yes citrus…limes, lemons, grapefruits, and oranges.
The Ruby-throated Hummingbirds (Archilochus colubris) are on the way toward the gulf states, then on to Central and South America. Five dashed by the rocky lookout in the falls this morning. Remember, keep your feeders clean, wash and rinse all the parts, and refill them with a fresh batch of “nectar”, four or five parts water to one part sugar. Repeating this process daily during hot weather should keep contamination from overtaking your feeder. It’s not a bad idea to rotate two feeders. Have one cleaned, rinsed, and air drying while the second is filled and in use at your feeding station, then just swap them around. Your equipment will be just as clean as it is at the sanitary dairy…you know, where they make sherbet.
The first of the season Caspian Terns (Hydroprogne caspia), giant freshwater versions of the terns you see at the seashore, passed through the falls late this morning. Their bills are blood-red, not orange like the more familiar terns on the coast. They’re stunning.
Ring-billed Gulls (Larus delawarensis) have been at the falls for several weeks. Total numbers and the composition of the age groups in the flock change over the days, so birds appear to be trickling through and are then replaced by others coming south. The big push of southbound migrants for this and many other species that winter locally in the Mid-Atlantic region and in the southern United States is still more than a month away. There are still plenty more birds to come after the hours of daylight are reduced and the temperatures take a dip.
A Ring-billed Gull on the lookout for a morning snack. They’ll eat almost anything and do a good job of keeping the river picked clean of the remains of animals that have met misfortune. They’ll linger around landfills, hydroelectric dams, and fast-food restaurant parking lots through the winter.Turkey Vultures (Cathartes aura) are common around the falls due to the abundance of carrion in the vicinity and because of the strong thermal updrafts of air over the sun-heated Pothole Rocks. These rising currents provide lift for circling vultures. We would expect migrating birds of a number of species will also take advantage of these thermals to gain altitude and extend the distance of their glides.
Some migrating butterflies were counted today. Cloudless Sulphurs, more of a vagrant than a migrant, and, of course, Monarchs. I’ll bet you know the Monarch, it’s black and orange. How can you miss them, colored orange.
That’s it, that’s all for now, I bid you adieu…I’m going to have a dip of orange sherbet, or two.
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It’s tough being good-looking and liked by so many. You’ve got to watch out, because popularity makes you a target. Others get jealous and begin a crusade to have you neutralized and removed from the spotlight. They’ll start digging to find your little weaknesses and flaws, then they’ll exploit them to destroy your reputation. Next thing you know, people look at you as some kind of hideous scoundrel.
Today, bright afternoon sunshine and a profusion of blooming wildflowers coaxed butterflies into action. It was one of those days when you don’t know where to look first.
A Pearl Crescent (Phyciodes tharos) sipping nectar from Rough Boneset (Eupatorium pilosum) flowers. Asters (Aster) are the host plants for the larvae of this butterfly.A Buckeye (Junonia coenia) on Rough Boneset. Its caterpillars are known to feed on members of the Acanthus family, possibly including the Water Willow (Justicia americana) which is so abundant in Conewago Falls.Visitors from south of the Mason-Dixon Line arrived on the recent warm winds. Two Cloudless Sulphurs (Phoebis sennae) patrolled the Riverine Grasslands, especially near the stands of Partridge Pea, a possible host plant. One is seen here visiting a Halbred-leaved Rose Mallow blossom. These large yellow butterflies are always a standout.
Purple Loosestrife (Lythrum salicaria) has a bad reputation. Not native to the Americas, this prolific seed producer began spreading aggressively into many wetlands following its introduction. It crowds out native plant species and can have a detrimental impact on other aquatic life. Stands of loosestrife in slow-moving waters can alter flows, trap sediment, and adversely modify the morphology of waterways. Expensive removal and biological control are often needed to protect critical habitat.
The dastardly Purple Loosestrife may have only two positive attributes. First, it’s a beautiful plant. And second, it’s popular; butterflies and other pollinators find it to be irresistible and go wild over the nectar.
A Silver-spotted Skipper (Epargyreus clarus) feeding on Purple Loosestrife nectar. The host plants for this common butterfly’s caterpillars are a wide variety of Legumes.A Cabbage White (Pieris rapae), a butterfly introduced from Europe in the 1800s, feeds on introduced Purple Loosestrife.A Wild Indigo Duskywing (Erynnis baptisiae) feeding on Purple Loosestrife. This butterfly has expanded its population and range by using the introduced Crown Vetch as a host plant.
Don’t you just adore the wonderful butterflies. Everybody does. Just don’t tell anyone that they’re pollinating those dirty filthy no-good Purple Loosestrife plants.
SOURCES
Brock, Jim P., and Kenn Kaufman. 2003. Butterflies of North America. Houghton Mifflin Company. New York.
Newcomb, Lawrence. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. Boston, Massachusetts.
