Emergence of the Turtles

Along the lower Susquehanna, an unseasonably mild day in early spring can provide an observer with the opportunity to witness an annual spectacle seldom seen by the average visitor to the river—concentrations of dozens, sometimes hundreds, of turtles as they emerge from their winter slumber to bathe in the year’s first surge of warm air and sunshine.

Reptiles of the Lower Susquehanna River Watershed: Snapping Turtle
Snapping Turtles (Chelydra serpentina) spend the winter buried in mud along the river shoreline and in nearby Alluvial Terrace Wetlands.  We photographed this one just as it was digging its way out.
Reptiles of the Lower Susquehanna River Watershed: Snapping Turtle
A cold and stiff Snapping Turtle crawls away from the shade toward sun-drenched shallows where it will have a chance to limber up.
Reptiles of the Lower Susquehanna River Watershed: Snapping Turtle
A cruise in open water loosens up the muscles and gets rid of some of the accumulations of sticky mud and muck.
Reptiles of the Lower Susquehanna River Watershed: Painted Turtles
Freshly emerged Painted Turtles clamber onto a log to bask in the cloud-filtered sun.
Reptiles of the Lower Susquehanna River Watershed: Painted Turtle atop a Snapping Turtle
A Painted Turtle looking for a place to get out of the chilly water soon discovered the obvious solution.
It’s catching on, more Painted Turtles atop a Snapping Turtle in an Alluvial Terrace Wetland.
Reptiles of the Lower Susquehanna River Watershed: Red-eared Slider and Common Map Turtle
The Common Map Turtle (right) is the turtle most frequently observed basking on rocks and logs along the main stem of the Susquehanna.  To the left is a Red-eared Slider (Trachemys scripta elegans), an increasingly numerous invasive species.  The first Red-eared Sliders arrived in the river as, you guessed it, unwanted pets.  Editor’s Note: Special thanks to the local Beaver (Castor canadensis) for trimming the trees and providing a clear shot for this photograph!
Reptiles of the Lower Susquehanna River Watershed: Red-eared Slider and Painted Turtles
And now, a quick quiz.  Name the things that don’t belong in this picture?  Here’s a hint: a non-native Red-eared Slider (left) joins indigenous Painted Turtles atop a discarded tire in an Alluvial Terrace Wetland in Dauphin County, Pennsylvania.

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.

City Life: Gulls, Dabbling Ducks, and More

So you aren’t particularly interested in a stroll through the Pennsylvania woods during the gasoline and gunpowder gang’s second-biggest holiday of the year—the annual sacrifice-of-the-White-tailed-Deity ritual.  I get it.  Two weeks and nothing to do.  Well, why not try a hike through the city instead?  I’m not kidding.  You might be surprised at what you see.  Here are some photographs taken today during several strolls in Harrisburg, Pennsylvania.

First stop was City Island in the Susquehanna River—accessible from downtown Harrisburg or the river’s west shore by way of the Market Street Bridge.

From the middle of the Susquehanna River, City Island offers a spectacular view of the downtown Harrisburg skyline.  In summer, it’s the capital city’s playground.  During the colder months, it’s a great place to take a quiet walk and find unusual birds.
This Bald Eagle was in mature trees along the river shoreline near the Harrisburg Senator’s baseball stadium.
Ring-billed Gulls gather on the “cement beach” at the north end of City Island.
One of a dozen or so Herring Gulls seen from the island’s north end. This particular bird is a juvenile.
A Ring-billed Gull and some petite Bonaparte’s Gulls.  Really good birders will tell you to always check through flocks of these smaller gulls carefully.  It turns out they’re onto something.  Look closely at the gull to the right.
A bright red bill and more of a crescent shape to the black spot behind the eye, that’s an adult Black-headed Gull (Chroicocephalus ridibundus) in winter plumage, a rare bird on the Susquehanna.  Black-headed Gulls have colonized North America from Europe, breeding in Iceland, southernmost Greenland, and rarely Newfoundland.

Okay, City Island was worth the effort.  Next stop is Wildwood Park, located along Industrial Road just north of the Pennsylvania Farm Show complex and the Harrisburg Area Community College (HACC) campus.  There are six miles of trails surrounding mile-long Wildwood Lake within this marvelous Dauphin County Parks Department property.

A flock of Killdeer at the south end of Wildwood Lake.  From November through February, a walk along the south and west sides of the impoundment can be a photographer’s dream. The light is suitable in the morning, then just keeps getting better as the day wears on.
Is this probable Carolina/Black-capped Chickadee hybrid a resident at Wildwood or just a visitor from a few miles to the north?  Currently, pure Black-capped Chickadees (Poecile atricapillus) nest in the mountains well to the north of Harrisburg, and pure Carolina Chickadees nest south of the city.  Harrisburg possibly remains within the intergrade/hybrid zone, an area where the ranges of the two species overlap, but probably not for long.  During recent decades, this zone has been creeping north, at times by as much as a half mile or more each year.  So if the capital city isn’t Carolina Chickadee territory yet, it soon will be.
Another chickadee likely to be a hybrid, this one with some white in the greater wing coverts like a Black-capped, but with a call even more rapid than that of the typical Carolina, the species known for uttering the faster “chick-a-dee-dee-dee”.  It sounded wired, like it had visited a Starbucks all morning.
In the lower Susquehanna valley, Carolina Chickadees have already replaced hybrids and pure Black-capped Chickadees as nesting birds in the Piedmont hills south of Harrisburg and the Great Valley.  This Carolina Chickadee was photographed recently in the Furnace Hills at Middle Creek Wildlife Management Area in northern Lancaster County.  The transition there was probably complete by the end of the twentieth century.  Note the characteristic overall grayish appearance of the wings and the neat lower border of the black bib on this bird, 
For comparison, a bird presumed to be a pure Black-capped Chickadee photographed earlier this month in Lebanon County, Pennsylvania.  This fall, “Black-caps”, like many other northern perching birds, are moving south to invade the lower elevations and milder climes of the Piedmont and Atlantic Coastal Plain Provinces.  Note the extensive areas of white in the wings, the long tail, the buffy flanks, and the jagged edge of the black bib.
Along Wildwood Lake’s west shore, an adult male Sharp-shinned Hawk was soon attracted to the commotion created by bantering chickadees and other songbirds.
Yellow during the first year, the eyes of the Sharp-shinned Hawk get redder as the bird ages.
Also along the west border of Wildwood Lake, temperatures were warm enough to inspire Painted Turtles (Chrysemys picta) to seek a sun bath atop logs in the flooded portions of the abandoned Pennsylvania Canal.

And now, without further ado, it’s time for the waterfowl of Wildwood Lake—in order of their occurrence.

A pair of Wood Ducks (hen left, drake right) with American Black Ducks and Canada Geese.
A pair of Northern Pintails.
A pair of American Wigeons (Mareca americana).
A hen (left) and drake (right) Gadwall.
Mallards.
A female Northern Shoveler.
An American Black Duck.
Canada Geese.
You just knew there had to be a booby prize, a “Blue Suede” (a.k.a. Blue Swede), a domestic variety of Mallard.
It’s a Green-winged Teal (Anas crecca) sampler.  Clockwise from left: a juvenile male, a female, and an adult male.
A drake and two hen Green-winged Teal.  Isn’t that great light by late afternoon?

See, you don’t have to cloak yourself in bright orange ceremonial garments just to go for a hike.  Go put on your walking shoes and a warm coat, grab your binoculars and/or camera, and have a look at wildlife in a city near you.  You never know what you might find.

SOURCES

Taylor, Scott A., Thomas A. White, Wesley M. Hochachka, Valentina Ferretti, Robert L. Curry, and Irby Lovette.  2014.  “Climate-Mediated Movement of an Avian Hybrid Zone”.  Current Biology.  24:6  pp.671-676.

State of Confusion

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.
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SOURCES

Committee on the Status of Endangered Wildlife in Canada.  2002.  Status Report of the Northern Map Turtle.  Canadian Wildlife Service.  Ottawa, Ontario.