Brown-headed Cowbird – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

March 3, 2024March 5, 2024

Snow Geese, Bald Eagles, and More at Middle Creek Wildlife Management Area

To take advantage of this unusually mild late-winter day, observers arrived by the thousands to have a look at an even greater number of migratory birds gathered at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area. Here are some highlights…

Trails at Middle creek Wildlife Management Area — Multitudes of Sunday hikers enjoyed the warm afternoon on Middle Creek’s many trails.

In one of Middle Creek’s numerous impoundments, newly emerged Painted Turtles bask in the sunshine.

Native blackbirds, particularly males including this Brown-headed Cowbird, are arriving to stake out a claim on suitable breeding territory.

Male Red-winged Blackbirds visit the feeding station at the Middle Creek W.M.A. Visitor’s Center.

Brown-headed Cowbird and Red-winged Blackbird — Brown-headed Cowbirds regularly maintain close association with Red-winged Blackbirds, a frequent victim of the former’s nest parasitism, the practice of laying and abandoning their eggs in a host species’ abode. By early May, adult “red-wings” can often be seen tending fledged cowbird young raised at the expense of their own progeny.

Common Grackles displaying. — Male Common Grackles display their colors in an attempt to establish dominance.

Visitor’s to Middle Creek’s Willow Point Trail not only had a chance to see thousands of geese and other waterfowl, but they might also get a good look at some of the handsome White-crowned Sparrows that have been there during recent weeks.

The first Tree Swallows of the season have arrived to stake a claim to nest boxes located throughout the refuge’s grasslands.

Bare croplands and muddy shorelines around Middle Creek’s lakes and ponds are attracting migrating Killdeer. Some will stay to nest.

Hundreds of Ring-billed Gulls arrived during the late afternoon to spend the night on the main lake.

A Red-tailed Hawk was seen hunting mice and exhibiting territorial behavior. It is probably protecting a nest site somewhere on the refuge.

Canada Geese could be seen coming and going, with migratory birds apparently supplementing the resident flock. This group flushed when a Bald Eagle passed close by.

Bald Eagles — You could hold a Bald Eagle I.D. clinic at Middle Creek W.M.A. right now. Dozens of birds of varying age classes could be seen in the trees surrounding the main lake and the larger ponds. Currently, fifty or more could be present. At least one Golden Eagle has been seen as well.

Adult Bald Eagle — An adult Bald Eagle in definitive plumage investigating the inhabitants of the lake.

Second-year Bald Eagle — This Bald Eagle in its second calendar year is not yet one year of age, but it has already begun replacing dark body feathers with a light plumage that will earn it the nickname “white belly” for this and its third year. It will start molting its long hatch-year (juvenile) flight feathers soon after its first birthday.

Second-year Bald Eagle and Red-tailed Hawk — Another second-year immature Bald Eagle, this one being scolded by the aforementioned territorial Red-tailed Hawk. Though showing some wear in the tail, this eagle still has a full set of lengthy hatch-year (juvenile) flight feathers and remains mostly dark below when compared to the bird of the same age class seen in the previous image. As in other birds, diet, genetics, stress, climatic conditions, and many other factors will frequently vary the timing of molt among individuals in a population of Bald Eagles.

Third-year Bald Eagle — An immature Bald Eagle in its third calendar year still retaining numerous long juvenile wing and tail feathers. In coming months, as it reaches its second birthday, it will begin replacing the remaining older plumage with a set of new flight feathers.

Fourth-year Bald Eagle — An immature Bald Eagle in its fourth calendar year approaches its third birthday with a rather conspicuous long juvenile feather remaining in each wing. These feathers will soon be replaced. In addition, the body plumage will darken, the head will begin to show more white, and the bill will become yellow. In about two more years, the bird will attain its familiar adult definitive plumage. Click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page to learn more about determining the age of these and other birds of prey.

Snow Geese and Observers at Middle Creek W.M.A. — Bald Eagles draw a crowd, but the real attraction at Middle Creek W.M.A. in late winter is Snow Geese,…

Snow geese at Middle Creek W.M.A. — Migratory Snow Geese, an annual spectacle at Middle Creek.

Snow Geese and hundreds of onlookers. — Snow Geese and hundreds of delighted onlookers.

Short-eared Owl at M.C.W.M.A. — As daylight waned and the Snow Geese returned to the main lake for the night, more than one hundred lucky observers were treated to the rare sight of several Short-eared Owls (Asio flammeus) emerging to hunt the refuge’s managed grasslands for mice and voles. For many of these visitors, it was a memorable first-time experience.

April 8, 2023April 8, 2023

Hidden Surprises

If you’re like us, you’re forgoing this year’s egg hunt due to the prices, and, well, because you’re a little bit too old for such a thing.

Instead, we took a closer look at some of our wildlife photographs from earlier in the week. We’ve learned from experience that we don’t always see the finer details through the viewfinder, so it often pays to give each shot a second glance on a full-size screen. Here are a few of our images that contained some hidden surprises.

We photographed these Blue-winged Teal and American Black Ducks as they were feeding in a meadow wetland…

..but upon closer inspection we located…

…a Common Green Darner patrolling for mosquitoes and other prey. The Common Green Darner is a migratory species of dragonfly. After mating, they deposit their eggs in wetland pools, ponds, and slow-moving streams.

We photographed this Water Strider as it was “walking” across a pool in a small stream that meanders through a marshy meadow…

..but after zooming in a little closer we found…

Water Strider with a Mosquito — …a mosquito coming to deposit its eggs had been seized as a mid-day meal. Look at how the legs of the Water Strider use the surface tension of the pool to allow it to “walk on water”, even while clutching and subduing its prey.

..but then, following further examination, we discovered…

THE BAD EGG

…but a careful search of the flock revealed…

Brown-headed Cowbirds and Red-winged Blackbirds — …three female Brown-headed Cowbirds among them (the unstreaked brown birds, two to the far left and one among the “red-wings” to the right). Cowbirds practice nest parasitism as a means of putting their young up for adoption. Red-winged Blackbirds and numerous other species are the unknowing victims. The female cowbird discreetly deposits her egg(s) in the adopting party’s nest and abandons it. The cowbird egg and the hatchling that follows is cared for by the victim species, often at the expense of their own young.

November 4, 2017September 4, 2019

Feathered Fallout

The NOAA National Weather Service radar images from last evening provided an indication that there may be a good fallout of birds at daybreak in the lower Susquehanna valley. The moon was bright, nearly full, and there was a gentle breeze from the north to move the nocturnal migrants along. The conditions were ideal.

Rising from daytime roosts in New York and Pennsylvania, then streaming south in moonlit skies, migrating birds are recorded as echoes on this post-sunset composite NEXRAD loop from last evening. (NOAA/National Weather Service image)

The Riparian Woodlands at Conewago Falls were alive with migrants this morning. American Robins and White-throated Sparrows were joined by new arrivals for the season: Brown Creeper (Certhia americana), Ruby-crowned Kinglets (Regulus calendula), Golden-crowned Kinglets (Regulus satrapa), Dark-eyed Junco (Junco hyemalis), and Yellow-rumped Warbler (Setophaga coronata). These are the perching birds one would expect to have comprised the overnight flight. While the individuals that will remain may not yet be among them, these are the species we will see wintering in the Mid-Atlantic states. No trip to the tropics for these hardy passerines.

American Robins continued migratory flight into the first hour of daylight this morning. Their calls are commonly heard at night as migrating individuals pass overhead.

White-throated Sparrows are nocturnal migrants, and are a familiar find on woodland edges and at suburban feeding stations through the winter.

Dark-eyed Juncos, also nocturnal migrants, are common winter residents in the Lower Susquehanna River Watershed, frequently visiting bird feeders.

Heavy rain earlier this week in the Susquehanna River drainage basin has flooded most of the Pothole Rocks; the rapids of Conewago Falls have returned.

CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS

October 28, 2017October 31, 2017

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.

October 7, 2017October 8, 2017

Summer Breeze

A moderate breeze from the south placed a headwind into the face of migrants trying to wing their way to winter quarters. The urge to reach their destination overwhelmed any inclination a bird or insect may have had to stay put and try again another day.

Blue Jays were joined by increasing numbers of American Robins crossing the river in small groups to continue their migratory voyages. Killdeer (Charadrius vociferous) and a handful of sandpipers headed down the river route. Other migrants today included a Cooper’s Hawk (Accipiter cooperii), Eastern Bluebirds (Sialia sialis), and a few Common Mergansers (Mergus merganser), House Finches (Haemorhous mexicanus), and Common Grackles (Quiscalus quiscula).

The afternoon belonged to the insects. The warm wind blew scores of Monarchs toward the north as they persistently flapped on a southwest heading. Many may have actually lost ground today. Painted Lady (Vanessa cardui) and Cloudless Sulphur butterflies were observed battling their way south as well. All three of the common migrating dragonflies were seen: Common Green Darner (Anax junius), Wandering Glider (Pantala flavescens), and Black Saddlebags (Tramea lacerata).

The warm weather and summer breeze are expected to continue as the rain and wind from Hurricane Nate, today striking coastal Alabama and Mississippi, progresses toward the Susquehanna River watershed during the coming forty-eight hours.

This Great Blue Heron was joined by numerous other fishermen and a good number of sightseers in the falls today.

A colorful young Northern Water Snake *(Nerodia sipedon)* takes advantage of the sun-heated surface of a Pothole Rock to remain nimble and active. Cooler weather will soon compel this and other reptiles to find shelter for winter hibernation.

September 30, 2017September 4, 2018

Swallows by the Thousands

A fresh breeze from the north brought cooler air and a reminder that summer is gone and autumn has arrived.

Fast-moving dark clouds provided a perfect backdrop for viewing passing diurnal migrants. Bald Eagles utilized the tail wind to cruise down the Susquehanna toward Chesapeake Bay and points further south. A migrating Merlin began a chase from which a Northern Flicker narrowly escaped by finding shelter among Pothole Rocks and a few small trees. The season’s first American Black Duck (Anas rubripes), Common Loon (Gavia immer), Yellow-bellied Sapsucker (Sphyrapicus varia), and American Pipits (Anthus rubescens) moved through.

Blue Jays continued their hesitant crossings of the river at Conewago Falls. The majority completed the journey by forming groups of a dozen or more birds and following the lead of a lone American Robin, a Northern Flicker, or, odd as it appeared, a small warbler.

By far the most numerous migrants today were swallows. Thousands of Northern Rough-winged Swallows and hundreds of Tree Swallows were on the wing in search of what was suddenly a sparse flying insect supply. To get out of the brisk wind, some of the more resourceful birds landed on the warm rocks. To satisfy their appetite, many were able to pick crawling arthropods from the surface of the boulders. They swallow them whole.