Only fools mess around with bees, wasps, and hornets as they collect nectar and go about their business while visiting flowering plants. Relentlessly curious predators and other trouble makers quickly learn that patterns of white, yellow, or orange contrasting with black are a warning that the pain and anguish of being zapped with a venomous sting awaits those who throw caution to the wind. Through the process of natural selection, many venomous and poisonous animals have developed conspicuously bright or contrasting color schemes to deter would-be predators and molesters from making such a big mistake.
Visual warnings enhance the effectiveness of the defensive measures possessed by venomous, poisonous, and distasteful creatures. Aggressors learn to associate the presence of these color patterns with the experience of pain and discomfort. Thereafter, they keep their distance to avoid any trouble. In return, the potential victims of this unsolicited aggression escape injury and retain their defenses for use against yet-to-be-enlightened pursuers. Thanks to their threatening appearance, the chances of survival are increased for these would-be victims without the need to risk death or injury while deploying their venomous stingers, poisonous compounds, or other defensive measures.
One shouldn’t be surprised to learn that over time, as these aforementioned venomous, poisonous, and foul-tasting critters developed their patterns of warning colors, there were numerous harmless animals living within close association with these species that, through the process of natural selection, acquired nearly identical color patterns for their own protection from predators. This form of defensive impersonation is known as Batesian mimicry.
Let’s take a look at some examples of Batesian mimicry right here in the Lower Susquehanna River Watershed.
Suppose for a moment that you were a fly. As you might expect, you would have plenty to fear while you spend your day visiting flowers in search of energy-rich nectar—hundreds of hungry birds and other animals want to eat you.
If you were a fly and you were headed out and about to call upon numerous nectar-producing flowers so you could round up some sweet treats, wouldn’t you feel a whole lot safer if you looked like those venomous bees, wasps, and hornets in your neighborhood? Wouldn’t it be a whole lot more fun to look scary—so scary that would-be aggressors fear that you might sting them if they gave you any trouble?
Suppose Mother Nature and Father Time dressed you up to look like a bee or a wasp instead of a helpless fly? Then maybe you could go out and collect sweets without always worrying about the bullies and the brutes, just like these flies of the lower Susquehanna do…
FLOWER FLIES/HOVER FLIES
So let’s review. If you’re a poor defenseless fly and you want to get your fair share of sweets without being gobbled up by the beasts, then you’ve got to masquerade like a strongly armed member of a social colony—like a bee, wasp, or hornet. Now look scary and go get your treats. HAPPY HALLOWEEN!
To pass the afternoon, we sat quietly along the edge of a pond created recently by North American Beavers (Castor canadensis). They first constructed their dam on this small stream about five years ago. Since then, a flourishing wetland has become established. Have a look.
Isn’t that amazing? North American Beavers build and maintain what human engineers struggle to master—dams and ponds that reduce pollution, allow fish passage, and support self-sustaining ecosystems. Want to clean up the streams and floodplains of your local watershed? Let the beavers do the job!
Have you purchased your 2023-2024 Federal Duck Stamp? Nearly every penny of the 25 dollars you spend for a duck stamp goes toward habitat acquisition and improvements for waterfowl and the hundreds of other animal species that use wetlands for breeding, feeding, and as migration stopover points. Duck stamps aren’t just for hunters, purchasers get free admission to National Wildlife Refuges all over the United States. So do something good for conservation—stop by your local post office and get your Federal Duck Stamp.
Still not convinced that a Federal Duck Stamp is worth the money? Well then, follow along as we take a photo tour of Bombay Hook National Wildlife Refuge. Numbers of southbound shorebirds are on the rise in the refuge’s saltwater marshes and freshwater pools, so we timed a visit earlier this week to coincide with a late-morning high tide.
As the tide recedes, shorebirds leave the freshwater pools to begin feeding on the vast mudflats exposed within the saltwater marshes. Most birds are far from view, but that won’t stop a dedicated observer from finding other spectacular creatures on the bay side of the tour route road.
No visit to Bombay Hook is complete without at least a quick loop through the upland habitats at the far end of the tour route.
We hope you’ve been convinced to visit Bombay Hook National Wildlife Refuge sometime soon. And we hope too that you’ll help fund additional conservation acquisitions and improvements by visiting your local post office and buying a Federal Duck Stamp.
When you were young, you may have selected your tennis shoes because they promised to make you run faster and jump higher. Remember those? Then as you got a bit older, you may have really wanted the brand that would get you noticed—those overpriced status-symbol athletic shoes. As the years went by and you put on the extra pounds in all the wrong places, maybe it occurred to you that it might be a really good idea to get some exercise. So you went out and bought some stylish and expensive fitness footwear that promised to help you run faster and jump higher—and wore that pair to go shopping at the grocery store. Then you finally realized…
Back in late May of 1983, four members of the Lancaster County Bird Club—Russ Markert, Harold Morrrin, Steve Santner, and your editor—embarked on an energetic trip to find, observe, and photograph birds in the Lower Rio Grande Valley of Texas. What follows is a daily account of that two-week-long expedition. Notes logged by Markert some four decades ago are quoted in italics. The images are scans of 35 mm color slide photographs taken along the way by your editor.
DAY SIX—May 26, 1983
“Bentsen State Park — Texas”
“Arose at 7:30. Birded the park and watched for the reported Roadside Hawk. No luck. A Roadrunner and Kiskadee was a welcome addition to our list.”
The appearance of Roadside Hawk (Rupornis magnirostris) north of the Rio Grande in Hidalgo County, Texas, was hot news in 1983. In the weeks leading up to our visit and while we were there, no sightings of this mega-rarity were confirmed. The reports that were received were not accompanied by photographs or sufficient details to rule out the Hook-billed Kites (Chondrohierax unicinatus) and Cooper’s Hawks that were known to be present. Roadside Hawk remains a very elusive tropical vagrant in the United States. It was seen as recently as December of 2018 along the man-made flood control levee to the east of Bentsen-Rio Grande Valley State Park near the Border Patrol Corral and the adjacent National Butterfly Center, neither of which were present in 1983.
Both the Greater Roadrunner (Geococcyx californianus), a familiar member of the cuckoo family (Cuculidae), and the Great Kiskadee (Pitangus sulphuratus), a flycatcher at the northern limit of its range in south Texas, were much anticipated finds at Bentsen-Rio Grande State Park. We would get better looks at both when we moved to the west in a couple of days.
“Traveled to Brownsville and met Harold and Steve at the airport at 12:30 P.M.”
Back in 1983, the Brownsville Airport was the most frequently used destination for those wanting to fly into the Lower Rio Grande Valley. Today, Valley International Airport in Harlingen is the busier of the two. Both of these airports have an interesting history from the World War II years. Brownsville Airport, renamed Brownsville Army Air Field for the duration of the war, was in use as a base for antisubmarine warfare flights, pilot training, aircraft engine overhauls, and the occasional servicing of B-29 bombers. The airport in Harlingen was founded during the period as Harlingen Army Air Field and was home to the Harlingen Aerial Gunnery School. A cheesy Hollywood propaganda movie called Aerial Gunner (1943) was shot there in late 1942 and starred Richard Arlen and a local actress, Amelita (Lita) Ward, who was discovered by the picture’s producers in Harlingen during the early stages of filming. A young Robert Mitchum portrays one of the gunners. It’s one of those typical B-movies of the period with a story line that is all mixed up with what happened years ago. A climactic part of the film depicts students being taken aloft to fire machine guns at kite-like targets being towed behind other training aircraft flying over the nearby Gulf of Mexico. You can find this classic and watch it for free on the internet. Afterward, you can go join up if you want, but you can no longer get the war bonds they were selling.
“We tried for the Clay-colored Robin — No Luck.”
Now that Harold and Steve had joined us, we began putting in an earnest effort to find the five species we all needed for our life lists—those Lower Rio Grande Valley exclusives Father Tom had given us directions to find. First up was Clay-colored Robin, known today as Clay-colored Thrush (Turdus grayi), a brown-colored bird similar to our American Robin. Its native range in 1983 was from northern Colombia north to the Rio Grande River. The only pair known to be reliably nesting north of the river in the United States, thus within the A.B.A. listing area, was in Brownsville in a park-like setting on the side of a small hill with a commercial radio station transmitter and antenna on its crest. It was an easy place to find in the otherwise flat landscape, but we had no luck finding the birds. Were we too late? Was nesting season over? Had the birds already dispersed?
“Visited Santa Ana again and added Ground Dove and White-tailed (Black-shouldered) Kite.”
Father Tom provided us with a tip that Hook-billed Kites had nested in the vicinity of Santa Ana National Wildlife Refuge. We remained vigilant, but saw none. The petite Common Ground Dove (Columbina passerina) was harder to locate than I expected, possibly because its small size makes it more prone to depredation than larger doves and pigeons, so it may be a little more secretive. White-tailed Kite (Elanus leucurus) sightings were a highlight of the trip, so graceful and stunning in appearance, but very wary and distant—not a good photo opportunity. Other sightings at Santa Ana included the first Harris’s Hawk (Parabuteo unicinctus) of the trip, White-tipped Dove, Groove-billed Ani, Barn Swallow, Black-crested Titmouse, Long-billed Thrasher, a lingering Solitary Vireo, Bronzed Cowbird, Olive Sparrow, and Northern Cardinal. We heard a Dickcissel (Spiza americana) in a sunflower field by the refuge entrance, but failed to see it.
Also at Santa Ana N.W.R. a Giant Toad and a Texas Tortoise (Gopherus berlandieri), a scrubland native of south Texas and northern Mexico.
“We arrived back at Bentsen State Park and I got supper ready while the others birded. At dusk we saw the Elf Owls again and toured the roads. Saw two Pauraques. To bed by 11:15 after a welcome shower.”
A White-eyed Vireo was found during our late afternoon walk. On a tip from Father Tom, we checked the campground in the area of the east restrooms for nesting Tropical Parulas (Setophaga pitiayumi). For each of us, it was another of the five target species for the trip. We heard nothing that resembled this warbler’s song, which sounds very much like that of the Northern Parula with which we were each familiar.
Nightjars are more often seen than heard, so having the opportunity to finish the day watching two Common Pauraques sail across a break in the forest to grab airborne insects was a real treat.
It may look like just a puddle in the woods, but this is a very specialized wetland habitat, a habitat that is quickly disappearing from the Lower Susquehanna River Watershed. It’s a vernal pool—also known as a vernal pond or an ephemeral (lasting a short time) pool or pond.
Viable vernal pools have several traits in common…
They contain water in the spring (hence the name vernal).
They have no permanent inflow or outflow of water.
They typically dry up during part of the year—usually in late summer.
They are fish-free.
They provide breeding habitat for certain indicator species of forest-dwelling amphibians and other animals.
They are surrounded by forest habitat that supports the amphibians and other vernal pool species during the terrestrial portion of their life cycle.
To have a closer look at what is presently living in this “black leaf” vernal pool, we’re calling on the crew of the S. S. Haldeman to go down under and investigate.
Let’s take it down for a better look. Dive, all dive!
We hope you enjoyed this quick look at life in a vernal pool. While the crew of the S. S. Haldeman decontaminates the vessel (we always scrub and disinfect the ship before moving between bodies of water) and prepares for its next voyage, you can learn more about vernal pools and the forest ecosystems of which they are such a vital component. Be sure to check out…
Following the deep freeze of a week ago, temperatures soaring into the fifties and sixties during recent days have brought to mind thoughts of spring. In the pond at susquehannawildlife.net headquarters, Green Frogs are again out and about.
But is this really an early spring? Migrating waterfowl indicate otherwise. Having been forced south from the Great Lakes during the bitter cold snap, a variety of our tardy web-footed friends belatedly arrived on the river and on the Susquehanna Flats of upper Chesapeake Bay about ten days ago. Now, rising water from snow melt and this week’s rains have forced many of these ducks onto local lakes and ponds where ice coverage has been all but eliminated by the mild weather. For the most part, these are lingering autumn migrants. Here’s a sample of some of the waterfowl seen during a tour of the area today…
With the worst of winter’s fury still to come, it’s time to say farewell to most of these travelers for a little while. With a little luck, we’ll see them again in March or April.
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.
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 mild winter has apparently minimized weather-related mortality for the local Green Frog population. With temperatures in the seventies throughout the lower Susquehanna valley for this first full day of spring, many recently emerged adults could be seen and, on occasion, heard. Yellow-throated males tested their mating calls—reminding the listener of the sound made by the plucking of a loose banjo string.
If you venture out, keep alert for the migrating birds of late winter and early spring.
If you’re staying close to home, be sure to check out the changing appearance of the birds you see nearby. Some species are losing their drab winter basic plumage and attaining a more colorful summer breeding alternate plumage.
So just how many Green Frogs were there in that first photograph? Here’s the answer.
Happy Spring. For the benefit of everyone’s health, let’s hope that it’s a hot and humid one!
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.
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.
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.
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.
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.
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.
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.
Committee on the Status of Endangered Wildlife in Canada. 2002. Status Report of the Northern Map Turtle. Canadian Wildlife Service. Ottawa, Ontario.