Photo of the Day

Zabulon Skipper on Pickerelweed
A female Zabulon Skipper visits a cluster of Pickerelweed blossoms.  The Zabulon Skipper is a small butterfly of our streamsides, riversides, damp meadows, and other moist grassy spaces.  The Pickerelweed is an emergent plant of lakes, ponds, and wetlands.  Add it to your next project to improve water quality and help pollinators like the Zabulon Skipper.  You may even attract a hummingbird or two!   

Two Feeders Are Better Than One

Dish-type Hummingbird Feeder

Over the coming six weeks or more, Ruby-throated Hummingbirds will be feeding throughout the daylight hours to fuel their long migration to the tropics for winter.  With plenty of adult and juvenile birds around, it’s the best time of year to get a better look at them by putting up a feeder.

You may already know the basics—hang the feeder near flower beds if you have them, keep it filled with a mixture of one part sugar to four parts water, and fill the little ant trap with fresh water.  And you may know too, that to provide for the birds’ safety you should avoid hanging your feeder near plate glass windows and you should keep it high enough to avoid ambushes by any predators which may be hiding below.

Now here’s a hummingbird feeding basic (a bird feeding basic really) that you may not have considered.  For every hummingbird feeder you intend to have filled and hanging in your garden, have a second one cleaned and air-drying to replace it when it’s time to refill.  Why?  Sugar water, like bird seed when it gets wet, is an excellent media for growing bacteria, molds, and other little beasties that can make birds (and people) sick.  In the summer heat, these microorganisms grow much faster than they would in the wintertime, so diligence is necessary.  Regularly, on a daily basis ideally, each feeder in your garden should be taken down and replaced with a clean, dry feeder filled with fresh sugar water mixture.  The cleaning process should include dumping of the feeder’s contents followed by a thorough scrubbing with soapy water to remove any food residues that, if left remaining, can provide nourishment for growing bacteria.  Next, the feeder should be rinsed with clean water to wash away soap and debris.  You can sanitize the feeder if you wish, but it is more important to allow it to air-dry until its next use.  Depriving mold, bacteria, and other microbes of moisture is a critical step in the process of eliminating them as a health hazard.

A Note of Caution: To avoid cross contaminating the utensils and space you use for preparing and serving meals, it’s important to have a separate work area with brushes, buckets, and other equipment dedicated only to bird feeder cleaning and drying.

Cleaning and air-drying a dish-type hummingbird feeder
Dish-type hummingbird feeders are easy to clean and fill.  They dry quickly to eliminate microbial reproduction.

So, let’s review.  If you’re going to have a hummingbird feeder filled with nectar hanging in your garden, you need a second one—clean, dry, and ready to replace it.

A hummingbird feeder in the garden and a clean dry and ready replacement
A hummingbird feeder hanging in the garden and a clean replacement air-drying.

If you’d like to attract more than one hummingbird at a time to your garden, you may want to place a second feeder where the territorial little bird claiming the first as its own can’t see it.  Then you’ll need four feeders—two hanging in the garden and two that are clean, dry, and ready to be filled with fresh sugar water to use as replacements.

Two hummingbird feeders in the garden and two clean dry and ready replacements
Two hummingbird feeders hanging in the garden and two replacements cleaned and air-drying.

If you’re in a rural area with good habitat, you may have four or more feeders around your refuge.  You’ll need a replacement feeder for each.

Four hummingbird feeders hanging in the garden
Four hummingbird feeders hanging and…
Four Hummingbird Feeders Cleaned and Air-drying
…four replacements cleaned and air-drying.

Remember, keep your feeders clean and filled with fresh nectar and you’ll be all set to enjoy the Ruby-throated Hummingbirds of late summer.  Then watch closely for the cold-hardy western species that visit the Lower Susquehanna River Watershed beginning in October.  The occurrence of at least one of these rarities in the Lower Susquehanna River Watershed each autumn is now something of a regular event.

Ruby-throated Hummingbirds at feeders
Ruby-throated Hummingbirds at feeders.

The Mexican Cigar

You’ve heard and read it before—native plants do the best job of providing sustenance for our indigenous wildlife.  Let’s say you have a desire to attract hummingbirds to your property and you want to do it without putting up feeders.  Well, you’ll need native plants that provide tubular flowers from which these hovering little birds can extract nectar.  Place enough of them in conspicuous locations and you’ll eventually see hummingbirds visiting during the summer months.  If you have a large trellis, pole, or fence, you might plant a Trumpet Vine, also known as Trumpet Creeper.  They become adorned with an abundance of big red-orange tubular flowers that our Ruby-throated Hummingbirds just can’t resist.  For consistently bringing hummingbirds to the garden, Trumpet Vine may be the best of the various plants native to the Mid-Atlantic States.

Trumpet Vine
The showy bloom clusters of Trumpet Vine are irresistible to Ruby-throated Hummingbirds.

There is a plant, not particularly native to our area but native to the continent, that even in the presence of Trumpet Vine, Pickerelweed, Partridge Pea, and other reliable hummingbird lures will outperform them all.  It’s called Mexican Cigar (Cuphea ignea) or Firecracker Plant.  Its red and yellow tubular flowers look like a little cigar, often with a whitish ash at the tip.  Its native range includes some of the Ruby-throated Hummingbird’s migration routes and wintering grounds in Mexico and the Caribbean Islands, where they certainly are familiar with it.

This morning in the susquehannawildlife.net headquarters garden, the Ruby-throated Hummingbird seen in the following set of images extracted nectar from the Mexican Cigar blossoms exclusively.  It ignored the masses of showy Trumpet Vine blooms and other flowers nearby—as the hummers that stop by usually do when Cuphea is offered.

Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea)Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea) Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea)Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea)Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea)Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea) Some garden centers still have Mexican Cigar plants available.  You can grow them in pots or baskets, then bring them inside before frost to treat them as a house plant through the winter.  Give the plants a good trim sometime before placing them outside when the weather warms in May.  You’ll soon have Ruby-throated Hummingbirds visiting again for the summer.

Ruby-throated Hummingbird and Mexican Cigar (Cuphea ignea)
  

Blooming in Early July: Great Rhododendron

With the gasoline and gunpowder gang’s biggest holiday of the year now upon us, wouldn’t it be nice to get away from the noise and the enduring adolescence for just a little while to see something spectacular that isn’t exploding or on fire?  Well, here’s a suggestion: head for the hills to check out the flowers of our native rhododendron, the Great Rhododendron (Rhododendron maximum), also known as Rosebay.

Great Rhododendron
The Great Rhododendron is an evergreen shrub found growing in the forest understory on slopes with consistently moist (mesic) soils.  The large, thick leaves make it easy to identify.  During really cold weather, they may droop and curl, but they still remain green and attached to the plant.

Thickets composed of our native heathers/heaths (Ericaceae) including Great Rhododendron, Mountain Laurel, and Pinxter Flower (Rhododendron periclymenoides), particularly when growing in association with Eastern Hemlock and/or Eastern White Pine, provide critical winter shelter for forest wildlife.  The flowers of native heathers/heaths attract bees and other pollinating insects and those of the deciduous Pinxter Flower, which blooms in May, are a favorite of butterflies and Ruby-throated Hummingbirds.

Pinxter Flower in bloom
A close relative of the Great Rhododendron is the Pinxter Flower, also known as the Pink Azalea.

Forests with understories that include Great Rhododendrons do not respond well to logging.  Although many Great Rhododendrons regenerate after cutting, the loss of consistent moisture levels in the soil due to the absence of a forest canopy during the sunny summertime can, over time, decimate an entire population of plants.  In addition, few rhododendrons are produced by seed, even under optimal conditions.  Great Rhododendron seeds and seedlings are very sensitive to the physical composition of forest substrate and its moisture content during both germination and growth.  A lack of humus, the damp organic matter in soil, nullifies the chances of successful recolonization of a rhododendron understory by seed.  In locations where moisture levels are adequate for their survival and regeneration after logging, impenetrable Great Rhododendron thickets will sometimes come to dominate a site.  These monocultures can, at least in the short term, cause problems for foresters by interrupting the cycle of succession and excluding the reestablishment of native trees.  In the case of forests harboring stands of Great Rhododendron, it can take a long time for a balanced ecological state to return following a disturbance as significant as logging.

Birds of Conewago Falls in the Lower Susquehanna River Watershed: Ruffed Grouse
Ruffed Grouse (Bonasa umbellus) may be particularly sensitive to the loss of winter shelter and travel lanes provided by thickets of Great Rhododendron and other members of the heather/heath family.  (Vintage 35 mm image)

In the lower Susquehanna region, the Great Rhododendron blooms from late June through the middle of July, much later than the ornamental rhododendrons and azaleas found in our gardens.   Set against a backdrop of deep green foliage, the enormous clusters of white flowers are hard to miss.

Great Rhododendron Flower Cluster
Great Rhododendrons sport an attractive blossom cluster.  The colors of the flower, especially the markings found only on the uppermost petal, guide pollinators to the stamens (male organs) and pistil (female organ).
Bumble Bee Pollinating a Great Rhododendron Flower
To this Bumble Bee (Bombus species), the yellowish spots on the uppermost petal of the Great Rhododendron may appear to be clumps of pollen and are thus an irresistible lure.  

In the Lower Susquehanna River Watershed, there are but a few remaining stands of Great Rhododendron.  One of the most extensive populations is in the Ridge and Valley Province on the north side of Second Mountain along Swatara Creek near Ravine (just off Interstate 81) in Schuylkill County, Pennsylvania.  Smaller groves are found in the Piedmont Province in the resort town of Mount Gretna in Lebanon County and in stream ravines along the lower river gorge at the Lancaster Conservancy’s Ferncliff and Wissler’s Run Preserves.  Go have a look.  You’ll be glad you did.

Great Rhododendron along Route 125 near Ravine
Great Rhododendron along Route 125 along the base of the north slope of Second Mountain north of Ravine, Schuylkill County, Pennsylvania.
Great Rhododendron along Swatara Creek
Great Rhododendrons beginning to bloom during the second week of July along Swatara Creek north of Ravine, Schuylkill County, Pennsylvania.  Note how acid mine drainage continues to stain the rocks (and pollute the water) in the upper reaches of this tributary of the lower Susquehanna.

Maximum Variety

You’ll want to go for a walk this week.  It’s prime time to see birds in all their spring splendor.  Colorful Neotropical migrants are moving through in waves to supplement the numerous temperate species that arrived earlier this spring to begin their nesting cycle.  Here’s a sample of what you might find this week along a rail-trail, park path, or quiet country road near you—even on a rainy or breezy day.

The Black-throated Blue Warbler is one of more than two dozen species of warblers passing through the Lower Susquehanna River Watershed right now.  Look for it in the middle and bottom branches of deciduous forest growth.
The Veery and other woodland thrushes sing a melodious song.  Veerys remain through the summer to nest in damp mature deciduous forests.
The American Redstart, this one a first-spring male, is another of the variety of warblers arriving now.  Redstarts nest in deciduous forests with a dense understory.
Adaptable inquisitive Gray Catbirds are here to nest in any shrubby habitat, whether in a forest or a suburban garden.
Blue-gray Gnatcatchers (Polioptilia caerulea) arrive in April, so they’ve been here for a while.  They spend most of their time foraging in the treetops.  The gnatcatcher’s wheezy call alerts the observer to their presence.
Look way up there, it’s a pair of Blue-gray Gnatcatchers building a nest.
The Eastern Phoebe, a species of flycatcher, often arrives as early as mid-March.  This particular bird and its mate are already nesting beneath a stone bridge that passes over a woodland stream.
Orchard Orioles (Icturus spurius) are Neotropical migrants that nest locally in habitats with scattered large trees, especially in meadows and abandoned orchards.
In the lower Susquehanna region, the Baltimore Oriole is a more widespread breeding species than the Orchard Oriole.  In addition to the sites preferred  by the latter, it will nest in groves of mature trees on farms and estates, in parks, and in forest margins where the canopy is broken.
The Warbling Vireo (Vireo  gilvus) nests in big trees along streams, often sharing habitat with our two species of orioles.
Eastern Towhees arrive in numbers during April.  They nest in thickets and hedgerows, where a few stragglers can sometimes be found throughout the winter.
The Yellow-breasted Chat (Icteria virens) is a migrant from the tropics that sometimes nests locally in thorny thickets.  Its song consists of a mixed variety of loud phrases, reminding the listener of mimics like catbirds, thrashers, and mockingbirds.
Thickets with fragrant blooms of honeysuckle and olive attract migrating Ruby-throated Hummingbirds.  Look for them taking a break on a dead branch where they can have a look around and hold on tight during gusts of wind.
The Eastern Kingbird, a Neotropical flycatcher, may be found near fields and meadows with an abundance of insects.  In recent years, high-intensity farming practices have reduced the occurrence of kingbirds as a nesting species in the lower Susquehanna valley.  The loss of pasture acreage appears to have been particularly detrimental.
Savannah Sparrows (Passerculus sandwichensis) can be found in grassy fields throughout the year.  Large parcels that go uncut through at least early July offer them the opportunity to nest.
Male Bobolinks have been here for just more than a week.  Look for them in alfalfa fields and meadows.  Like Savannah Sparrows, Bobolinks nest on the ground and will lose their eggs and/or young if fields are mowed during the breeding cycle.
Cattail marshes are currently home to nesting Swamp Sparrows.  Wetlands offer an opportunity to see a variety of unique species in coming weeks.
Shorebirds like this Solitary Sandpiper will be transiting the lower Susquehanna basin through the end of May.  They stop to rest in wetlands, flooded fields, and on mudflats and alluvial islets in the region’s larger streams.  Many of these shorebirds nest in far northern Canada.  So remember, they need to rest and recharge for the long trip ahead, so try not to disturb them.

Smoke from a Distant Fire

Have a look at these images of the smoke plume being generated by fires in forests and other wildlands in the western United States.

Smoke from enormous wildfires located primarily in California and Oregon obscures ground features across the Mid-Atlantic States this morning.  Lake Ontario and the Finger Lakes of New York are the most readily identifiable landmarks in the center of the image.  The Lower Susquehanna River Watershed is indiscernible beneath the dense blanket of haze.  (CIRA/NOAA image)
This morning’s satellite image of the United States and the North Atlantic looks like an illustration one might find in a meteorology textbook showing examples of a variety of extreme atmospheric phenomena.  There’s something going on everywhere.  (CIRA/NOAA image)
Here we’ve labeled the major stuff.  There are two hurricanes (Sally and Teddy), a tropical storm (Vicky), and three tropical depressions, each labeled “T.D.”.  A strong cold front in central Canada is making its way toward the eastern United States.  Dust from the Sahara continues to stream into the Americas and the gray-brown plume of smoke from wildfires in the Pacific Coast States stretches thousands of miles east into the North Atlantic.  (CIRA/NOAA base image)

While viewing these amazing images, consider for a moment the plight of migrating birds.  Each one struggles to survive the energy-depleting effects of wind, distance, storm, cold, drought, dust, and sometimes even smoke as it strives to reach its breeding grounds each spring and its wintering grounds each fall.  Natural and man-made effects can cause migrating birds to become disoriented.  Songbirds are known to become lost at sea.  Others strike objects including buildings and radio towers, particularly when visibility is impaired.  The dangers seem endless.

Neotropical migrants must somehow navigate the maze of perils that lie between their breeding grounds in the north and their wintering habitats in tropical climates (designated here using blue stars).  (CIRA/NOAA base image)

For migrating birds, places of refuge where they can stop to feed and rest during their long journeys are essential to their survival.  For species attempting flights through conditions as extreme as those seen in these images, there is the potential for significant loss of life, particularly among the birds with less than optimal stores of energy.

During their southbound autumn migration to tropical wintering grounds in Central America, some Ruby-throated Hummngbirds will attempt a non-stop flight across the Gulf of Mexico, a route requiring maximum stores of energy.  Keep those feeders clean and full of fresh provisions!

Bird Migration Highlights

The southbound bird migration of 2020 is well underway.  With passage of a cold front coming within the next 48 hours, the days ahead should provide an abundance of viewing opportunities.

Here are some of the species moving through the lower Susquehanna valley right now.

Blue-winged Teal are among the earliest of the waterfowl to begin southward migration.
Sandpipers and plovers have been on the move since July.  The bird in the foreground with these Killdeer is not one of their offspring, but rather a Semipalmated Plover (Charadrius semipalmatus), a regular late-summer migrant in the Lower Susquehanna River Watershed.
Hawk watch sites all over North America are counting birds right now.  The Osprey is an early-season delight as it glides past the lookouts.  Look for them moving down the Susquehanna as well.
Bald Eagles will be on the move through December.  To see these huge raptors in numbers, visit a hawk watch on a day following passage of a cold front when northwest winds are gusting.
Merlins were seen during this past week in areas with good concentrations of dragonflies.  This particular one at Middle Creek Wildlife Management Area in Lancaster and Lebanon Counties…
…was soon visited by another.
Check the forest canopy for Yellow-billed Cuckoos.  Some local birds are still on breeding territories while others from farther north are beginning to move through.
Ruby-throated Hummingbirds are darting through the lower Susquehanna valley on their way to the tropics.  This one has no trouble keeping pace with a passing Tree Swallow.
Nocturnal flights can bring new songbirds to good habitat each morning.  It’s the best time of year to see numbers of Empidonax flycatchers.  But, because they’re often silent during fall migration, it’s not the best time of year to easily identify them.  This one lacking a prominent eye ring is a Willow Flycatcher (Empidonax traillii).
During the past two weeks, Red-eyed Vireos have been numerous in many Susquehanna valley woodlands.  Many are migrants while others are breeding pairs tending late-season broods.
During mornings that follow heavy overnight flights, Blackburnian Warblers have been common among waves of feeding songbirds.
Chestnut-sided Warblers are regular among flocks of nocturnal migrants seen foraging among foliage at sunrise.
Scarlet Tanagers, minus the brilliant red breeding plumage of the males, are on their way back to the tropics for winter.
While passing overhead on their way south, Bobolinks can be seen or heard from almost anywhere in the lower Susquehanna valley.  Their movements peak in late August and early September.
During recent evenings, Bobolinks have been gathering by the hundreds in fields of warm-season grasses at Middle Creek Wildlife Management Area.
If you go to see the Bobolinks there, visit Stop 3 on the tour route late in the afternoon and listen for their call.  You’ll soon notice their wings glistening in the light of the setting sun as they take short flights from point to point while they feed.  Note the abundance of flying insects above the Big Bluestem and Indiangrass in this image.  Grasslands like these are essential habitats for many of our least common resident and migratory birds.

Clean Slate for 2020

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.

Yellowlegs for Breakfast

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

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.
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SOURCES

Klots, Elsie B.  1966.  The New Field Book of Freshwater Life.  G. P. Putnam’s Sons.  New York, NY.

Strangers In The Night

We all know that birds (and many other animals) migrate.  It’s a survival phenomenon which, above all, allows them to utilize their mobility to translocate to a climate which provides an advantage for obtaining food, enduring seasonal weather, and raising offspring.

In the northern hemisphere, most migratory birds fly north in the spring to latitudes with progressively greater hours of daylight to breed, nest, and provide for their young.  In the southern hemisphere there are similar movements, these to the south during their spring (our autumn).  The goal is the same, procreation, though the landmass offering sustenance for species other than seabirds is limited “down under”.  Interestingly, there are some seabirds that breed in the southern hemisphere during our winter and spend our summer (their winter) feeding on the abundant food sources of the northern oceans.

Each autumn, migratory breeding birds leave their nesting grounds as the hours of sunlight slowly recede with each passing day.  They fly to lower latitudes where the nights aren’t so long and the climate is less brutal.  There, they pass their winter season.

Food supply, weather, the start/finish of the nesting cycle, and other factors motivate some birds to begin their spring and autumn journeys.  But overall, the hours of daylight and the angle of the sun prompt most species to get going.

But what happens after birds begin their trips to favorable habitats?  Do they follow true north and south routes?  Do they fly continuously, day and night?  Do they ease their way from point to point, stopping to feed along the way?  Do they all migrate in flocks?  Well, the tactics of migration differ widely from bird species to species, from population to population, and sometimes from individual to individual.  The variables encountered when examining the dynamics of bird migration are seemingly endless, but fascinatingly so.  Bird migration is well-studied, but most of its intricacies and details remain a mystery.

Consider for a moment that just 10,000 years ago, an Ice Age was coming to an end, with the southernmost edge of the most recent glaciers already withdrawn into present-day Canada from points as near as the upper Susquehanna River watershed.  Back then, the birds migrating to the lower portion of the drainage basin each spring probably weren’t forest-dwelling tropical warblers, orioles, and other songbirds.  The migratory birds that nested in the lower Susquehanna River valley tens of millennia ago were probably those species found nesting today in taiga and tundra much closer to the Arctic Circle.  And the ancestors of most of the tropical migrants that nest here now surely spent their entire lives much closer to the Equator, finding no advantage by journeying to the frigid Susquehanna valley to nest.  It’s safe to say that since those times, and probably prior to them, migration patterns have been in a state of flux.

During the intervening years since the great ice sheets, birds have been able to adapt to the shifts in their environment on a gradual basis, often using their unmatched mobility to exploit new opportunities.  Migration patterns change slowly, but continuously, resulting in differences that can be substantial over time.  If the natural transformations of habitat and climate have kept bird migration evolving, then man’s impact on the planet shows great potential to expedite future changes, for better or worse.

Now, let’s look at two different bird migration strategies, that of day-fliers or diurnal migrants, and that of night-fliers, the nocturnal migrants.

Diurnal migrants are the most familiar to people who notice birds on the move.  The majority of these species have one thing in common, some form of defense to lessen the threat of becoming the victim of a predator while flying in daylight.  Of course the vultures, hawks, and eagles fly during the day.  Swallows and swifts employ speed and agility on the wing to avoid becoming prey, as do hummingbirds.  Finches have an undulating flight, never flying on a horizontal plane, which makes their capture more difficult.  Other songbirds seen migrating by day, Red-winged Blackbirds for example, congregate into flocks soon after breeding season to avoid being alone.  Defense flocks change shape constantly as birds position themselves toward the center and away from the vulnerable fringes of the swarm.  The larger the flock, the safer the individual.  For a lone bird, large size can be a form of protection against all but the biggest of predators.  Among the more unusual defenses is that of birds like Indigo Buntings and other tropical migrants that fly across the Gulf of Mexico each autumn (often completing a portion of the flight during the day), risking exhaustion at sea to avoid the daylight hazards, including numerous predators, found in the coastal and arid lands of south Texas.  Above all, diurnal migrants capture our attention and provide a spectacle which fascinates us.  Perhaps diurnal migrants attract our favor because we can just stand or sit somewhere and watch them go by.  We can see, identify, and even count them.  It’s fantastic.

What about a bird like the Canada Goose (Branta canadensis)?  It is often seen migrating in flocks during the day (the truly migratory ones flying much higher than the local year-round resident “transplants”), but then, during the big peak movements of spring and fall, they can be heard overhead all through the night.  Perhaps the Canada Goose and related waterfowl bridge the gap between day and night, introducing us to the secretive starlight and moonshine commuters, the nocturnal migrants.

The high-flying migratory Canada Goose can be seen during the daytime and heard at night when passing over the lower Susquehanna River valley.  A large flight exiting from Chesapeake Bay in late February or early March often results in a 12 to 24 hour-long stream of northbound flocks.

The skies are sometimes filled with thousands of them, mostly small perching birds and waders.  These strangers in the night fly inconspicuously in small groups or individually, and most can be detected when passing above us only when heard making short calls to remain in contact with their travel partners.  They need not worry about predators, but instead must have a method of finding their way.  Many, like the Indigo Bunting, can navigate by the stars, a capability which certainly required many generations to refine.  The nocturnal migrants begin moving just after darkness falls and ascend without delay to establish a safe flight path void of obstacles (though lights and tall structures can create a deadly counter to this tactic).  Often, the only clue we have that a big overnight flight has occurred is the sudden appearance of new bird species or individuals, on occasion in great numbers, in a place where we observe regularly.  Just days ago, the arrival of various warbler species at Conewago Falls indicated that there was at least a small to moderate movement of these birds during previous nights.

In recent years, the availability of National Weather Service radar has brought the capability to observe nocturnal migrants into easy reach.  Through the night, you can log on to your local National Oceanic and Atmospheric Administration’s National Weather Service radar page (State College for the Conewago Falls area) and watch on the map as the masses of migrating bird pass through the sweep of the radar beam.  As they lift off just after nightfall, rising birds will create an echo as they enter the sweeping beam close to the radar site.  Then, due to the incline of the transmitted signal and the curvature of the earth, migrants will be displayed as an expanding donut-like ring around the radar’s map location as returns from climbing birds are received from progressively higher altitudes at increasing distances from the center of the site’s coverage area.  On a night with a local or regional flight, several radar locations may show signs of birds in the air.  On nights with a widespread flight, an exodus of sorts, the entire eastern half of the United States may display birds around the sites.  You’ll find the terrain in the east allows it to be well-covered while radars in the west are less effective due to the large mountains.  At daybreak, the donut-shaped displays around each radar site location on the map contract as birds descend out of the transmitted beam and are no longer detected.

Weather systems sometimes seem to motivate some flights and stifle others.  The first example seen below is a northbound spring exodus, the majority of which is probably migrants from the tropics, the Neotropical migrants, including our two dozen species of warblers.  A cold front passing into the northeastern United States appears to have stifled any flight behind it, while favorable winds from the southwest are motivating a heavy concentration ahead of the front.

National Oceanic and Atmospheric Administration/National Weather Service radar image from May 5, 2010, at 11:18 PM EDT, shows rain associated with a cold front moving east from the border of Ontario, Canada, and the United States into New England and the Mid-Atlantic region.  The heavy blue and green reflections surrounding the radar locations ahead of the front are nocturnal migrating birds taking advantage of favorable conditions for flight including a tail wind from the southwest.  Note the lighter migration behind the advancing front.  Heavy radar echoes on the gulf coast, particularly in Texas, indicate dense bird concentrations exiting the tropics to fan out into North American breeding areas.  The westward progression of expanding echoes surrounding individual radar sites indicates birds rising into the radar beam at local nightfall.

The second and third examples seen below are an autumn nocturnal migration movement, probably composed of many of the same tropics-bound species which were on the way north in the previous example.  Note that during autumn, the cold front seems to motivate the flight following its passage.  Ahead of the front, there is a reduced and, in places, undetectable volume of birds.  The two images below are separated by about 42 hours.

National Oceanic and Atmospheric Administration/National Weather Service radar image (still) from September 5, 2017, at 2:38 AM EDT, shows rain in the northeast associated with a slow-moving cold front stretching from Maine southwest to New Mexico.  Heaviest nocturnal bird flights can be seen behind the advancing front where there are favorable tail winds from the north or northwest.
Nearly two full days later, the slow-moving cold front from the previous image has crossed Pennsylvania.  As nightfall progresses from east to west, ascending nocturnal migrants enter NEXRAD radar beams, their echoes creating expanding rings around individual sites.  Concentrations of southbound birds can be seen along the gulf coast.  Many will follow the Texas coastline into Mexico.  The Neotropical migrants that try to cross the Gulf of Mexico this night could be in for a perilous voyage.  Hurricane Katia is churning in the southern gulf and a much stronger storm, Hurricane Irma, is rolling toward the Bahamas and Florida from the southeast.  Masses of birds that follow learned routes or instinct to venture offshore and cross seas under such circumstances could suffer catastrophic losses.  (NOAA/National Weather Service image)

You can easily learn much more about birds (and insects and bats) on radar, including both diurnal and nocturnal migrants, by visiting the Clemson University Radar Ornithology Laboratory (CUROL) website.  There you’ll find information on using the various mode settings on NEXRAD (Next-Generation Radar) to differentiate between birds, other flying animals, and inanimate airborne or grounded objects.  It’s superbly done and you’ll be glad you gave it a try.

SOURCES

Clemson University Radar Ornithology Laboratory (CUROL) website:   http://virtual.clemson.edu/groups/birdrad/    as accessed September 6, 2017.

 

Suggestive Selling

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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Harvey Passes By

Rain from the remnants of Hurricane/Tropical Storm Harvey ended just after daybreak this morning.  Locally, the precipitation was mostly absorbed into the soil.   There was little runoff and no flooding.  The river level at Conewago Falls is presently as low as it has been all summer.  Among the pools and rapids of the Pothole Rocks, numbers of migrating birds are building.

Mist and a low cloud ceiling created poor visibility while trying to see early morning birds, but they’re here.  The warblers are moving south and a small wave of them was filtering through the foliage on the edge of the Riparian Woodlands.  One must bend backwards to have a look, and most could not be identified due to the poor lighting in the crowns of the trees where they were zipping about.  Five species of warblers and two species of vireos were discerned.

There are increasing concentrations of swallows feeding on insects over the falls.  Hundreds were here today, mostly Tree Swallows (Tachycineta bicolor).  Bank Swallows (Stelgidopteryx riparia) numbered in the hundreds, far below the thousands, often 10,000, which staged here for migration and peaked during the first week of September annually during the 1980s and 1990s.  Their numbers have been falling steadily.  Loss of nesting locations in embankments near water may be impacting the entire population.  A reduction in the abundance of late-summer flying insects here on the lower Susquehanna River may be cause for them to abandon this area as a migration staging point.

Bank and Tree Swallows by the hundreds were feeding upon flying insects above the waters of Conewago Falls today.  Lesser numbers of Northern Rough-winged Swallows (Stelgidopteryx serripennis) and Barn Swallows (Hirundo rustica) joined the swarm.

Clear weather in the coming nights and days may get the migrants up and flying in large numbers.  For those species headed to the tropics for winter, the time to get moving has arrived.

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Birds of a Feather-The Basics

When we look at birds, we are fascinated by the unique structure and appearance of their feathers.  They set birds apart from all other life forms on the planet.  Feathers enable most birds to achieve a feat long envied by humans…flight.  Birds on the wing awaken a curiosity in man.  They are generally the largest animals one will see in the air.  People want to know the name of a bird they see flying by, and want to know more about it.  The method and style of bird flight can aid an observer who attempts to determine which of the world’s 10,000 bird species he or she is studying.  Body shape and bird sounds often tell us a lot about the birds we encounter.  But most often, we rely on the unique colors, patterns, and shapes of the feathers, the plumage, to identify the bird we are seeing.

To birds, feathers are survival.  They are lightweight and strong to support the mechanics of flight.  Feathers are superb insulators against the elements, and provide additional buoyancy for birds spending time on the water.  For most birds, feathers provide a coloration and a texture similar to their surroundings, enabling them to hide from predators or to stalk prey.  In the case of some species, extravagant showy plumage is acquired, at least during the breeding season, and often only by males, as a way to attract a mate, intimidate rivals, defend a territory, or lure an intruder away from a nest site.  Because they become worn and damaged, all feathers are periodically molted and replaced by fresh plumage.

The feathers worn by a young bird leaving the nest are called the juvenile plumage.  Typically, this is followed by a molt into a basic (non-breeding) plumage.  The oft times extravagant breeding feathers are the result of a molt into an alternate (breeding) plumage.

While making field observations, the species, subspecies, gender, age, and other vital statistics of a bird can often by discerned easily by noting the plumage.  In the case of some other birds, diligence, experience, research, and an exceptionally good look and/or a photograph may be required to interpret these particulars.  In still other instances, a trained expert with a specimen in the hand is the only method of learning the bird’s identity and background.

This juvenile House Wren (Troglodytes aedon) left the nest wearing plumage very similar to that of its parents.  In lieu of bright colors, the male House Wren relies upon a vigorous bubbly song and a scrappy demeanor to defend its breeding territory.  This species nests in cavities on the edges of the Riparian Woodlands of Conewago Falls.  Males may have more than one mate.  House Wrens probably migrate at night and will winter in the southern border states and further south.

The age at which birds acquire adult breeding and non-breeding plumages varies by species.  Many juvenile birds resemble adults in basic (non-breeding) plumage as soon as they leave the nest.  For these birds, there is little difference between their juvenile plumage and the appearance of the feathers which follow the molt into their first basic (non-breeding) plumage.  Bird species which sexually mature within their first year may acquire their first basic (non-breeding) plumage before arrival of their first winter, followed by an alternate (breeding) plumage by their first spring.  This is particularly true for smaller short-lived birds.  Other species, normally larger long-lived ones, may experience a sequence of molts through multiple basic (non-breeding) plumages over a period of years prior to resembling an adult.  Some of these species, such as eagles, retain their juvenile plumage for as long as a year before extensive molting into a first basic (non-breeding) plumage begins.  Still others, including many gulls, attain a first-winter (formative) plumage prior to molting into their first basic (non-breeding) set of feathers.  Sexual maturity and initiation of an annual molt to alternate (breeding) plumage, if there is one, may take as long as three to five years for these bigger birds.

For nearly all species of birds, the molts which produce basic (non-breeding) plumage occur on at least an annual basis and include a total replacement of feathers.  This process renews worn and missing plumes including the flight feathers of the wings and tail.  Any molt to alternate (breeding) plumage often excludes the replacement of the feathers of the wings and tail.  There are many exceptions to these generalities.

A mid-summer nesting species, the American Goldfinch, Spinus tristis, male (left and right) molts into a glamorous alternate plumage for the breeding season.  The adult female’s alternate plumage (top) is a subdued green-yellow and black.  Her feathers resemble the foliage around the nest and offer protection from discovery during incubation.  Juvenile plumage (bottom) is similar to that of the female, but duller with a buffy tone.  By November each of these birds will have molted into a tan-buff basic (non-breeding) plumage, the male’s with a slight yellow hue.  During their first spring, juveniles attain sexual maturity and, like the adults from the previous year, molt into alternate (breeding) plumage.  The breeding birds seen here will probably winter in the southern United States, and birds that nested to our north will arrive to remain as winter residents.  Various stages of molt can be seen simultaneously during spring and autumn migrations as populations of goldfinches from multiple latitudes intermingle as they pass through the Susquehanna River watershed.
This juvenile Spotted Sandpiper (Actitis macularius), lacks the namesake dark markings on its white underside, thus it presently resembles an adult in basic (non-breeding) plumage.  Upon reaching sexual maturity, it will molt into a spotted alternate (breeding) plumage for the nesting season during each remaining year of its life.  Females of this species defend a territory and lay eggs in a nest located among cover near the shoreline.  A female may have as many as five mates.  Males alone incubate the eggs, usually four, for 20-24 days.  The young leave the nest upon hatching and are escorted by the male for about two to three additional weeks.  They are the only sandpiper to nest on the Susquehanna River shoreline.  Spotted Sandpipers migrate to the southern border states and further south for winter.  At Conewago Falls, they arrive in late April to nest, with birds, possibly migrants from further north, remaining until well into October.  In any plumage, you can easily recognize the Spotted Sandpiper by its habit of teetering its body at the hips to pump the tail up and down.
Bald Eagles go through a series of five molts before reaching adult plumage.  The first plumage, Juvenile, is nearly all dark brown with white linings along the forward underside of the wings.  The wing and tail feathers are a bit longer than in later plumages to aid the inexperienced birds during their clumsy first flights.  Due to the additional feather length, Juveniles look larger than older birds, but they are not as heavy as their seniors.  The bird seen here flying above Conewago Falls is probably in its second year.  This plumage, Basic I, also known as “White Belly I”, is characterized by a nearly full set of new flight feathers.  Note that some of the longer Juvenile feathers are still present, giving the wings a jagged sloppy look, particularly near the center of the trailing edge.  Third-year (Basic II) birds often have at least some white belly feathers and are sometimes known as “White Belly II” Bald Eagles.  Basic II birds typically possess a complete set of adult flight feathers, so the trailing edge of the wing has a neater and more uniform appearance.

The Bald Eagle in the two photographs above is in its first year.  This plumage, known as “Juvenile”, is characterized by dark flight feathers which appear uniformly long in length when the bird is airborne.  The eye is dark brown.  The iris of the eye will lighten in the second year (Basic I) and will become cream-colored by the third year (Basic II).  The bill, which is all dark gray when the bird is in the nest, has begun the slow progression to a yellow color that will be complete in the bird’s fifth year (Basic IV).  Third year (Basic II) birds molt to white crown and throat feathers, but have a dark set of feathers through the eye producing an “Osprey face” in most individuals.  In its fourth year (Basic III), this eagle will molt to a white tail with just a thin dark brown terminal band.  The head will become nearly all white except for a few dark spots through the eye, which will have a yellow iris.  A cleaner white head and tail will develop during the fifth year (Basic IV) and will persist through the familiar adult Bald Eagle plumages (Definitive Plumage) for the remainder of its life.

The Juvenile and non-breeding (basic) plumages of late-summer may seem drab and confusing, but learning them is a worthwhile endeavor.  Consider that most of the birds coming south during the migration will be adorned in this fashion.  The birds of North America are in their greatest numerical mass of the year right now, and nearly all are females, juveniles, other non-adults, or molting males.  There are few males in breeding plumage among the autumn waves of migrants.  In the coming months, there will be an abundance of opportunities to enjoy these marvels on wings, so getting to know the birds in non-breeding feathers is time well spent.  Make haste and get ready.  For our feathered friends, it’s autumn and they’re on their way south.

Here come the confusing fall migrants.  Twelve Semipalmated Sandpipers (Calidris pusilla) and sixteen unidentified “peep” sandpipers (Calidris species) were seen feeding in Conewago Falls on August 27.  This Semipalmated Sandpiper is either an adult in worn alternate (breeding) plumage or a Juvenile.  Adults of this species molt into basic plumage on the wintering grounds.  The Semipalmated Sandpiper breeds in the high arctic tundra and winters in the West Indies and northern South America.
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SOURCES

Dunne, Pete.  2006.  Pete Dunne’s Essential Field Guide Companion.  Houghton Mifflin Company.  New York.

Hayman, Peter; John Marchant, and Tony Prater.  1986.  Shorebirds, An Identification Guide to the Waders of the World.  Houghton Mifflin Company.  New York.

Kauman, Kenn.  1996.  Lives of North American Birds.  Houghton Mifflin Company.  New York.

McCullough, Mark A.  1989.  Molting Sequence and Aging Of Bald Eagles.  The Wilson Bulletin.  101:1-10.