Photo of the Day

A juvenile Red-headed Woodpecker surveys the morning landscape.  In the lower Susquehanna watershed, Red-headed Woodpeckers are an uncommon summer breeder requiring large dead oak trees in semi-open habitat for nesting.  They can occasionally be found during winter in mature oak woods, appearing most frequently west of the river at places including Gifford Pinchot State Park.  Fall migrants are seen along local ridges in September and October.

Forest vs. Woodlot

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.

Spotted Lanternfly in the Lower Susquehanna River Watershed

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.

Anthropoavians

Temperatures plummeted to well below freezing during the past two nights, but there was little sign of it in Conewago Falls this morning.  The fast current in the rapids and swirling waters in flooded Pothole Rocks did not freeze.  Ice coated the standing water in potholes only in those rocks lacking a favorable orientation to the sun for collecting solar heat during the day to conduct into the water during the cold nights.

On the shoreline, the cold snap has left its mark.  Ice covers the still waters of the wetlands.  Frost on exposed vegetation lasted until nearly noontime in shady areas.  Insect activity is now grounded and out of sight.  The leaves of the trees tumble and fall to cover the evidence of a lively summer.

The nocturnal bird flight is narrowing down to just a few species.  White-throated Sparrows, a Swamp Sparrow (Melospiza georgiana), and Song Sparrows are still on the move.  Though their numbers are not included in the migration count, hundreds of the latter are along the shoreline and in edge habitat around the falls right now.  Song Sparrows are present year-round, migrate at night, and are not seen far from cover in daylight, so migratory movements are difficult to detect.  It is certain that many, if not all of the Song Sparrows here today have migrated and arrived here recently.  The breeding population from spring and summer has probably moved further south.  And many of the birds here now may remain for the winter.  Defining the moment of this dynamic, yet discrete, population change and logging it in a count would certainly require different methods.

Song Sparrows are now abundant in the brushy edges of fields and woodlands.  They may even break into song on sunny days.

Diurnal migration was foiled today by winds from southerly directions and moderating temperatures.  The only highlight was an American Robin flight that extended into the morning for a couple of hours after daybreak and totaled over 800 birds.  This flight was peppered with an occasional flock of blackbirds.  Then too, there were the villains.

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They’re dastardly, devious, selfish, opportunistic, and abundant.  Today, they were the most numerous diurnal migrant.  Their numbers made this one of the biggest migration days of the season, but they are not recorded on the count sheet.  It’s no landmark day.  They excite no one.  For the most part, they are not recognized as migrants because of their nearly complete occupation of North America south of the taiga.  If people build on it or alter it, these birds will be there.  They’re everywhere people are.  If the rotten attributes of man were wrapped up into one bird, an “anthropoavian”, this would be it.

Meet the European Starling (Sturnus vulgaris).  Introduced into North America in 1890, the species has spread across the entire continent.  It nests in cavities in buildings and in trees.  Starlings are aggressive, particularly when nesting, and have had detrimental impacts on the populations of native cavity nesting birds, particularly Red-headed Woodpeckers, Purple Martins (Progne subis), and Eastern Bluebirds.  They commonly terrorize these and other native species to evict them from their nest sites.  European Starlings are one of the earlier of the scores of introduced plants and animals we have come to call invasive species.

Noisy flocks of European Starlings are right at home on man-made structures in city and country.

Today, thousands of European Starlings were on the move, working their way down the river shoreline and raiding berries from the vines and trees of the Riparian Woodlands.  My estimate is between three and five thousand migrated through during the morning.  But don’t worry, thousands more will be around for the winter.

European Starlings mob a Sharp-shinned Hawk from above, a common behavior.
An Eastern Bluebird feeds on the few berries left untouched by passing European Starlings.

Summer Breeze

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.
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Blue Jay Way

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.

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