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.

A Quick Getaway

It was a placid morning on Conewago Falls with blue skies dotted every now and then by a small flock of migrating robins or blackbirds.  The jumbled notes of a singing Winter Wren (Troglodytes hiemalis) in the Riparian Woodland softly mixed with the sounds of water spilling over the dam.  The season’s first Wood Ducks (Aix sponsa), Blue-winged Teal (Spatula discors), Herring Gull (Larus argentatus), Horned Larks (Eremophila alpestris), and White-throated Sparrows (Zonotrichia albicollis) were seen.

There was a small ruckus when one of the adult Bald Eagles from a local pair spotted an Osprey passing through carrying a fish.  This eagle’s effort to steal the Osprey’s catch was soon interrupted when an adult eagle from a second pair that has been lingering in the area joined the pursuit.  Two eagles are certainly better than one when it’s time to hustle a skinny little Osprey, don’t you think?

But you see, this just won’t do.  It’s a breach of eagle etiquette, don’t you know?  Soon both pairs of adult eagles were engaged in a noisy dogfight.  It was fussing and cackling and the four eagles going in every direction overhead.  Things calmed down after about five minutes, then a staring match commenced on the crest of the dam with the two pairs of eagles, the “home team” and the “visiting team”, perched about 100 feet from each other.  Soon the pair which seems to be visiting gave up and moved out of the falls for the remainder of the day.  The Osprey, in the meantime, was able to slip away.

In recent weeks, the “home team” pair of Bald Eagles, seen regularly defending territory at Conewago Falls, has been hanging sticks and branched tree limbs on the cross members of the power line tower where they often perch.  They seem only to collect and display these would-be nest materials when the “visiting team” pair is perched in the nearby tower just several hundred yards away…an attempt to intimidate by homesteading.  It appears that with winter and breeding time approaching, territorial behavior is on the increase.

The second migrating Osprey of the day ran the gauntlet of marauding eagles without incident.

In the afternoon, a fresh breeze from the south sent ripples across the waters among the Pothole Rocks.  The updraft on the south face of the diabase ridge on the east shore was like a highway for some migrating hawks, falcons, and vultures.  Black Vultures (Coragyps atratus) and Turkey Vultures streamed off to the south headlong into the wind after leaving the ridge and crossing the river.  A male and female Northern Harrier (Circus hudsonius), ten Red-tailed Hawks, two Red-shouldered Hawks (Buteo lineatus), six Sharp-shinned Hawks, and two Merlins crossed the river and continued along the diabase ridge on the west shore, accessing a strong updraft along its slope to propel their journey further to the southwest.  Four high-flying Bald Eagles migrated through, each following the east river shore downstream and making little use of the ridge except to gain a little altitude while passing by.

(Top and Middle) Turkey Vultures riding the fresh breeze and teetering to-and-fro on up-tilted wings.  This wing posture is known as a dihedral.  (Bottom) More than 100 migrating Black Vultures climbed high on the afternoon breeze to make an oblique crossing of the river and maintain a southbound course.

Late in the afternoon, the local Bald Eagles were again airborne and cackling up a storm.  This time they intercepted an eagle coming down the ridge toward the river and immediately forced the bird to climb if it intended to pass.  It turned out to be the best sighting of the day, and these “home team” eagles found it first.  It was a Golden Eagle (Aquila chrysaetos) in crisp juvenile plumage.  On its first southward voyage, it seemed to linger after climbing high enough for the Bald Eagles to loose concern, then finally selected the ridge route and crossed the river to head off to the southwest.

Ring-billed Gulls began feeding during the afternoon as clouds preceding stormy weather approached.
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