Shorebirds on the Mud in York County, Pennsylvania

At Lake Redman just to the south of York, Pennsylvania, a draw down to provide drinking water to the city while maintenance is being performed on the dam at neighboring Lake Williams, York’s primary water source, has fortuitously coincided with autumn shorebird migration.  Here’s a sample of the numerous sandpipers and plovers seen today on the mudflats that have been exposed at the southeast end of the lake…

Least Sandpiper at Lake Redman, York County, Pennsylvania.
One of a hundred or more Least Sandpipers seen on mudflats at Lake Redman today.
 A Semipalmated Plover and a Least Sandpiper at Lake Redman, York County, Pennsylvania.
A Semipalmated Plover and a Least Sandpiper
Pectoral Sandpipers at Lake Redman, York County, Pennsylvania.
Pectoral Sandpipers.
A Pectoral Sandpiper and Least Sandpipers at Lake Redman, York County, Pennsylvania.
A Pectoral Sandpiper and two Least Sandpipers.
A Semipalmated Sandpiper at Lake Redman, York County, Pennsylvania.
A Semipalmated Sandpiper.
A Stilt Sandpiper at Lake Redman, York County, Pennsylvania.
A Stilt Sandpiper feeding.
Stilt Sandpiper consuming an edible at Lake Redman, York County, Pennsylvania.
Stilt Sandpiper consuming an edible.
Stilt Sandpiper at rest at Lake Redman, York County, Pennsylvania.
Stilt Sandpiper at rest.
A Solitary Sandpiper at Lake Redman, York County, Pennsylvania.
A Solitary Sandpiper
A Lesser Yellowlegs at Lake Redman, York County, Pennsylvania.
A Lesser Yellowlegs.
A Greater Yellowlegs at Lake Redman, York County, Pennsylvania.
A Greater Yellowlegs.
Osprey at Lake Redman, York County, Pennsylvania.
Stirring up the shorebird crowd every now and then were several Ospreys, but all would soon be back to the business of feeding in the mud.
An Osprey hovers above shallow water near the mudflats as it searches for fish.
An Osprey hovers above shallow water near the mudflats as it searches for fish.

Not photographed but present at Lake Redman were at least two additional species of shorebirds, Killdeer and Spotted Sandpiper—bringing the day’s tally to ten.  Not bad for an inland location!  It’s clearly evident that these waders overfly the lower Susquehanna valley in great numbers during migration and are in urgent need of undisturbed habitat for making stopovers to feed and rest so that they might improve their chances of surviving the long journey ahead of them.  Mud is indeed a much needed refuge.

Shorebirds and Stormwater Retention Ponds

Your best bet for finding migrating shorebirds in the lower Susquehanna region is certainly a visit to a sandbar or mudflat in the river.  The Conejohela Flats off Washington Boro just south of Columbia is a renowned location.  Some man-made lakes including the one at Middle Creek Wildlife Management Area are purposely drawn down during the weeks of fall migration to provide exposed mud and silt for feeding and resting sandpipers and plovers.  But with the Susquehanna running high due to recent rains and the cost of fuel trending high as well, maybe you want to stay closer to home to do your observing.

Fortunately for us, migratory shorebirds will drop in on almost any biologically active pool of shallow water and mud that they happen to find.  This includes flooded portions of fields, construction sites, and especially stormwater retention basins.  We stopped by a new basin just west of Hershey, Pennsylvania, and found more than two dozen shorebirds feeding and loafing there.  We took each of these photographs from the sidewalk paralleling the south shore of the pool, thus never flushing or disturbing a single bird.

Stormwater retentrion basin.
Designed to prevent stream flooding and pollution, this recently installed stormwater retention basin along US 322 west of Hershey, Pennsylvania, has already attracted a variety of migrating plovers and sandpipers.
Killdeer
Killdeer stick close to exposed mud as they feed.
Least Sandpipers
Two of more than a dozen Least Sandpipers found busily feeding in the inch-deep water.
Lesser Yellowlegs
A Lesser Yellowlegs searching for small invertebrates.
Lesser Yellowlegs
Two Lesser Yellowlegs work out a disagreement.
Male Twelve-spotted Skimmers patrol the airspace above a pair of Least Sandpipers.
Male Twelve-spotted Skimmers patrol the airspace above a pair of Least Sandpipers. Dragonflies and other aquatic insects are quick to colonize the waters held in well-engineered retention basins.  Proper construction and establishment of a functioning food chain/web in these man-made wetlands prevents them from becoming merely temporary cesspools for breeding mosquitos.

So don’t just drive by those big puddles, stop and have a look.  You never know what you might find.

A Semipalmated Sandpiper (middle right) joins a flock of Least Sandpipers.
A Semipalmated Sandpiper (middle right) joins a flock of Least Sandpipers.
Pectoral Sandpipers (two birds in the center) are regular fall migrants on the Susquehanna at this time of year.
Pectoral Sandpipers (two birds in the center) are regular fall migrants on the Susquehanna at this time of year.  They are most frequently seen on gravel and sand bars adjacent to the river’s grassy islands, but unusually high water for this time of year prevents them from using this favored habitat.  As a result, you might be lucky enough to discover Pectoral Sandpipers on almost any mudflat in the area.
Two Pectoral Sandpipers and five smaller but very similar Least Sandpipers.
Two Pectoral Sandpipers and five smaller, but otherwise very similar, Least Sandpipers.
A Killdeer (right), a Semipalmated Plover (upper right), and a Least and Pectoral Sandpiper (left).
A Killdeer (right), a Semipalmated Plover (upper right), and Least and Pectoral Sandpipers (left).

Photo of the Day

Shorebird identification can be notoriously difficult, but it’s a skill best learned with practice.  Now is a good time to become familiar with the two most common species of plovers found in the lower Susquehanna valley.  Numbers of both are increasing on local mudflats as waves of southbound migrants begin to arrive.  The Killdeer in the lower left is a familiar nesting species of barren fields, stone parking lots, and gravel roofs.  Its numbers swell during spring and fall migration, with some lingering into winter until either snow cover or a hard freeze prompts them to finally depart for milder climes.  The Semipalmated Plovers in the upper right are strictly a migratory species in our area, nesting in northern Canada and Alaska and wintering along the American coastlines from Oregon and Delmarva south to Chile and Argentina.  You’ll notice that the Semipalmated Plover has just a single neck ring while the Killdeer has two.  That’s how you can tell them apart in a jiffy.  It’s that easy.

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.