Birds Beginning to Wander

Since Tuesday’s  snow storm, the susquehannawiildlife.net headquarters garden continues to bustle with bird activity.

Northern Mockingbird
Our Northern Mockingbird remains ever vigilant in its attempts to discourage American Robins and Eastern Bluebirds from feeding on the berry crop.  Slowly, the latter species are winning the contest.
Carolina Chickadee feeding on sunflower seed.
A Carolina Chickadee carefully dissects a sunflower seed to snack on the nutritious kernel.
Red-bellied Woodpecker
This beauty shows us that yes, Red-bellied Woodpeckers do indeed have red bellies.
American Robin eating Common Winterberry fruits.
Getting energized for a big move north, the robins keep on gulping berries.

Today, there arrived three species of birds we haven’t seen here since autumn.  These birds are, at the very least, beginning to wander in search of food.  Then too, these may be individuals creeping slowly north to secure an advantage over later migrants by being the first to establish territories on the most favorable nesting grounds.

Song Sparrow
This Song Sparrow is the first we’ve seen in the garden since sometime last fall.  Is it working its way north or did it just come to town in search of food?
Northern Flicker
Northern Flickers regularly spend the winter in small numbers in the Lower Susquehanna River Watershed.  This is the first one we’ve had visit the garden since late last autumn.
Fish Crows feeding on Eastern Red Cedar berries.
Fish Crows, seen here feeding on the fruits adorning an Eastern Red Cedar, have returned after being absent in our neighborhood since November.  In coming weeks, both they and the more numerous American Crows that remained through winter will begin constructing nests in nearby trees.

They say the early bird gets the worm.  More importantly, it gets the most favorable nesting spot.  What does the early birder get?  He or she gets out of the house and enjoys the action as winter dissolves into the miracle of spring.  Do make time to go afield and marvel a bit, won’t you?  See you there!

Photo of the Day

Soaring Bald Eagle
It’s time to keep an eye on the sky when you’re out and about.  Not only are mated pairs of Bald Eagles beginning their nesting cycle throughout the Lower Susquehanna River Watershed, but migrating birds are passing through the area on their way to breeding grounds farther north. This one drew the ire of pairs of Fish Crows and American Crows as it soared above the susquehannawildlife.net headquarters earlier today.

Essential Ice

Two days ago, widespread rain fell intermittently through the day and steadily into the night in the Susquehanna drainage basin.  The temperature was sixty degrees, climbing out of a three-week-long spell of sub-freezing cold in a dramatic way.  Above the ice-covered river, a very localized fog swirled in the southerly breezes.

By yesterday, the rain had ended as light snow and a stiff wind from the northwest brought sub-freezing air back to the region.  Though less than an inch of rain fell during this event, much of it drained to waterways from frozen or saturated ground.  Streams throughout the watershed are being pushed clear of ice as minor flooding lifts and breaks the solid sheets into floating chunks.

Today, as their high flows recede, the smaller creeks and runs are beginning to freeze once again.  On larger streams, ice is still exiting with the cresting flows and entering the rising river.

Ice chunks on Swatara Creek merge into a dense flow of ice on the river in the distance.  Swatara Creek is the largest tributary to enter the Susquehanna in the Gettysburg Basin.  The risk of an ice jam impounding the Swatara here at its mouth is lessened because rising water on the river has lifted and broken the ice pack to keep it moving without serious impingement by submerged obstacles.  Immovable ice jams on the river can easily block the outflow from tributaries, resulting in catastrophic flooding along these streams.
Fast-moving flows of jagged ice race toward Three Mile Island and Conewago Falls.  The rising water began relieving the compression of ice along the shoreline during the mid-morning.  Here on the river just downstream of the mouth of Swatara Creek, ice-free openings allowed near-shore piles to separate and begin floating away after 10:30 A.M. E.S.T.  Moving masses of ice created loud rumbles, sounding like a distant thunderstorm.
Ice being pushed and heaved over the crest of the York Haven Dam at Conewago Falls due to compression and rising water levels.
Enormous chunks of ice being forced up and over the York Haven Dam into Conewago Falls and the Pothole Rocks below.
Ice scours Conewago Falls, as it has for thousands of years.
The action of ice and suspended abrasives has carved the York Haven Diabase boulders and bedrock of Conewago Falls into the amazing Pothole Rocks.
The roaring torrents of ice-choked water will clear some of the woody growth from the Riverine Grasslands of Conewago Falls.
To the right of center in this image, a motorcar-sized chunk of ice tumbles over the dam and crashes into the Pothole Rocks.  It was one of thousands of similar tree-and-shrub-clearing projectiles to go through the falls today.

The events of today provide a superb snapshot of how Conewago Falls, particularly the Diabase Pothole Rocks, became such a unique place, thousands of years in the making.  Ice and flood events of varying intensity, duration, and composition have sculpted these geomorphologic features and contributed to the creation of the specialized plant and animal communities we find there.  Their periodic occurrence is essential to maintaining the uncommon habitats in which these communities thrive.

Fish Crows (Corvus ossifragus) gather along the flooding river shoreline.  Soon there’ll be plenty of rubbish to pick through, some carrion maybe, or even a displaced aquatic creature or two to snack upon.

Piles of Green Tape

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.