Watching Bald Eagles, gulls, and other winter birds at Conowingo Dam, Maryland
A site for gulls and Bald Eagles
Published: January 1, 2000
|Perhaps it's the massive white cloud of 20,000 to 100,000 gulls rising in glorious disarray from the turgid tailrace of northeastern Maryland's Conowingo Dam that attracts the winter crowds. For most visitors, it's almost certainly the 20 to 50 Bald Eagles intermixed with the gulls, at or below eye level, that provide the main attraction. The many ducks, herons, and raptors along the river below the dam add to the excitement. And for many birders, the chance to find a rare bird among the thousands of common ones provides overwhelming incentive to spend a day and to keep returning.|
Bald Eagles galore
Although there's enough variety here to appeal to a wide variety of birdwatching interests, the 96-foot-high dam's marquee attraction is, of course, the Bald Eagle. From November through February, dozens of eagles congregate just below the dam. They come to feast on gizzard shad, small fish that are stunned or diced as they are flushed through the dam's mighty turbine wheels and disgorged into the tailrace. They also enjoy pickings of carp and channel catfish in the river. These three fish species make up 95 percent of the eagles' winter diet here.
Conowingo may well have the most viewable gathering of eagles anywhere on the East Coast. There may be more individuals at a few other places, but not "in your face" as they are here. Organized eagle watches at the dam have drawn up to 400 people.
Robert Schutsky, who runs a birdwatching guide service in the area, has seen eagles at the dam stealing fish from gulls, Great Blue Herons, and even each other. "They're real opportunists," he notes. Typically, there are two immature eagles with mottled plumage for each white-hooded adult at Conowingo, and the adults often take advantage of the young ones when they catch fish.
Schutsky has had a chuckle or two through his years of watching birds at Conowingo. Once, about a mile below the dam, he watched an eagle whose eyes were bigger than its craw. The eagle swooped down and hooked a carp so big it dragged the bird of prey into the drink. Unable to unlock its talons, the hapless bird had to use its wings to paddle to shore.
You may also catch sight of the regal raptors as they soar on thermals, gather sticks for nearby nests, or - the home run of eagle watching - lock talons and somersault in a midair courtship. But you're most likely to catch them sitting and watching and waiting on huge transmission towers on an island just below the dam, in trees on either side of the river, or on rocks that pock the open water.
The congregating eagles are a combination of residents from a growing local population on the Chesapeake Bay and migrants from northern states, especially those surrounding the Great Lakes. The eagles at Conowingo are stirring evidence of the comeback of this great bird, which is in the process of being taken off the federal endangered species list.
The local birds breed just 12 miles below Conowingo on the Chesapeake Bay at the vast Aberdeen Proving Grounds, an Army weapons-testing facility with miles of off-limits shoreline. There, pairs of nesting eagles have soared from 41 in 1972 to 232 pairs in 1998. The reliable winter feeding ground below the dam has contributed to this remarkable recovery, notes Glenn Therres, a Bald Eagle expert with the Maryland Department of Natural Resources. The bay often freezes over, making the Conowingo tailrace a crucial source of winter sustenance.
The eagles may be the most intrinsically interesting, but for sheer numbers, nothing at Conowingo Dam matches the gull spectacle. As the dam begins releasing water from the upstream reservoir, "there's a Pavlovian response when the gulls hear the sirens and see the flashing red lights," says Gene Scarpulla, a Towson, Maryland, birder who spends most winter Sundays at the dam. Reacting to the dinner bell, gulls come streaming in from far away. Their food finding calls carry to other gulls for up to three miles.
Gull concentrations can soar from 2,000 to 25,000 in a matter of twenty minutes. "It looks like a blizzard, there are so many gulls in the air," says June Vaughn, a former naturalist for PECO Energy Company, the dam's operator. Often, two or three birds will swoop for the same fish and squabble in midair.
For the gulls, as for the eagles, the star attractions are the gizzard shad, silvery members of the herring family. Shad numbers have exploded after being introduced into the Conowingo Reservoir above the dam in the 1970s. On a good day, as many as one million are eaten by gulls as finger food. Gulls dip for the silvery shad; pull them off the surface in their beaks; then rest and devour the easy pickings on rocks, frozen sheets of ice, and the long concrete wing walls that radiate from the dam.
The majority of the tens of thousands of gulls that flock here in the winter are migrants from the Great Lakes and frozen waters in New England states. The most common species are Ring-billed, Herring, Great Black-backed, and Bonaparte's Gulls. They discovered the dam's never frozen tailrace and its delicatessen of fish nuggets about twenty years ago and have made it a favorite winter resort ever since. Numbers fluctuate depending on the severity of ice conditions to the north and on the frequency of water releases through the turbines at the dam.
Nowhere in the mid-Atlantic have there been so many species of gulls as at this spot. Among the 15 or 16 species of gulls sighted here are birds like Thayer's, California, and Franklin's Gulls - species normally found in the western United States. Other rarities include the European subspecies of Mew Gull, Black-headed Gull, and Little Gull, all normally found in Europe. The Lesser Black-backed Gull, another European visitor, was considered a rare species in Maryland until gullets at Conowingo began seeing it regularly. Birders are still debating whether or not the dam hosted a Slaty-backed Gull, which is normally an Asian species, last winter. Not quite so rare, but still fun to see, are Black-legged Kittiwakes, which are normally found out at sea during winter, and Arctic birds such as Iceland and Glaucous Gulls that are near the southern edge of their winter range. Only one species of gull - the Laughing Gull - is more likely to be seen in the summertime than in winter.
|Conowingo Dam is in north-eastern Maryland just north of Interstate 95 between Phildelphia and Baltimore - one of the most heavily traveled stretches of road in the country. From I-95, take Exit 93 (with signs to Perryville, Rising Sun, and Port Deposit), go north on Route 222 for about eight miles, then turn left (south) on Route 1 across the dam, turn left again onto Shuresville Road, and follow the signs. For more information, calll the Muddy Run Information Center at (717) 284-5861 or visit the Harford Bird Club's Conowingo Dam Web site.|
January and February are the best months for watching gulls, with good numbers from November through March. Bald Eagles are usually found year round at Conowingo, with peak numbers November through February. Top numbers of ducks and other waterbirds depend on when (and if) more northern lakes freeze over.
For the best viewing spots for gulls and eagles, check out the handicapped-accessible birding platform off the parking area, below the dam; the fisherman's catwalk along the face of the dam; the edge of the parking lot (from within your vehicle); or the riverbank (a short walk from the parking lot). Admission is free.
To bird above the dam, go east on Route 1 across the dam and turn left on Route 222. After about one mile, turn left on Mt. Zoar Road; pass a small boat launch; cross an old metal bridge; and after about a half mile pull over into the wide spot on the left side of the road that has room for two or three cars. This spot used to allow vehicular access to the railroad tracks, but it is now blocked to cars by a barrier. You can walk around the barrier, cross the railroad tracks, and observe the river above the dam from a gravel road that parallels the railroad tracks. Be very careful when crossing the tracks because they still support train traffic.
Birds below the dam
As if the eagles and gulls aren't enough
to enjoy, Great Blue Herons also put on quite a show at Conowingo.
Perhaps a hundred pairs nest below the dam, and the unoccupied nests
can be seen throughout the winter. By the end of February, the herons
begin prebreeding activities; and you might see them pairing up,
carrying big sticks, or visiting the nesting trees. Even in the heart
of winter, as many as a hundred great blues can be seen loafing or
feeding below the dam.
A feeding great blue usually stands
quietly at the water's edge looking for fish. However, Scarpulla has
observed a feeding behavior that is rarer and much more active. When
water flows through the dam and down the river, a heron will
occasionally fly toward the dam, land in the river, and float passively
downriver while actively feeding on fish. After perhaps a half mile,
the bird will jump out of the water and fly to the dam to start the
process over again.
Joining the fall and winter dining below the
dam are a variety of other fish-eating birds, including Common
Mergansers, Belted Kingfishers, and Black-crowned Night-Herons. Among
the Common Mergansers, you may be able to pick out one of the rarer (at
Conowingo) Red-breasted Mergansers. (See "Field Identification," page
90, to learn the differences between the two.)
Many raptors can
also be found near the dam. For the past two winters, a Peregrine
Falcon - removed from the endangered species list only last year -
spent much of the season perched on the superstructure of the dam. In
some winters, a Golden Eagle might be seen sitting in trees among the
Bald Eagles. Ospreys can be seen at the dam in the warmer months, but
not in winter, when some immature Bald Eagles may be mistaken for
The river below the dam is a good place to learn how to
tell the grayer American Black Ducks from the browner female Mallards.
Other species of dabbling ducks may be found along the river, along
with some species of diving ducks (especially Common Goldeneye and
Bufflehead), occasional Common Loons, and Pied-billed and Horned Grebes.
along the river shelters a good number and variety of woodpeckers and
songbirds. Two local winter specialties are Pileated Woodpecker, which
can be seen flying from tree to tree, and Winter Wren, which hides in
the dense brush near the river.
Above the dam
variety of waterbirds can be seen on the river above the dam, but
access to viewing areas is difficult (see sidebar for specific
directions). A gravel road parallels the active railroad tracks on the
east side of the river. If you walk north along the gravel road a short
way, you will soon see the mouth of Glen Cove across the river. Walk to
the south, and you will come to the dam.
The river above the dam
hosts as many as 20,000 Common Mergansers, plus both Red-breasted and
Hooded Mergansers. Among the diving ducks, Buffleheads, Common
Goldeneyes, and both Greater and Lesser Scaup are expected; and other
ducks of many species are possible, but unpredictable.
area can be a good inland location for a variety of birds that are
usually found along the seacoast in winter, including Great Cormorant,
Oldsquaw, and all three scoter species. Common Loons are expected here
in winter, and Red-throated Loons are possible.
Most of the
gulls seen below the dam can also be seen above, usually roosting close
to the structure itself. Bonaparte's and Ring-billed Gulls frequently
feed along the river.
Four Common Gulls
The four common species of gulls at Conowingo differ greatly in size, from the large great black-back to herring, ring bill, and the small Bonaparte's. Gull identification can be very challenging, however, as young of different species look more similar to each other than to adults of their own kind. Large gulls, such as Conowingo's herrings and great black-backs, take four years to attain adult plumage, and the winter plumage of each age group is distinctive but variable.
The immatures of the four most common gulls at Conowingo all have pink legs and black bills, but leg and bill color provide helpful field marks for identifying winter adults. Visitors can pick out an adult Bonaparte's by its red legs and an adult ring-bill by its yellow legs; in contrast, adult great black-backs and herrings retain the pinkish legs of their youth. Adult Bonaparte's have black bills, while great black-backs and herrings have yellow bills with a red spot. The adult ring-bill has a distinctive black ring circling its yellow bill.
Once the common species are learned, many birders return to the dam to find and identify the rarities, using a similar approach of determining size and comparing field marks. For help with your identification challenges, you should check out the second edition of Peter Grant's Gulls: A Guide to Identification and two videos, Large Gulls of North America and Small Gulls of North America, by John Vanderpoel. All three are sold by American Birding Association Sales at (800) 634-7736.
Conowingo's popularity as a birding mecca
is growing. When Eirik Blom, a birder from nearby Bel Air, Maryland,
started visiting the dam fourteen years ago, he had the place to
himself. Now, he says, on a good Saturday in January he may be joined
by as many as 100 other birders. Some of those birders belong to one of
the many bird clubs located within a few hours' drive - in Maryland,
Pennsylvania, Delaware, or New Jersey - that lead treks to the winter
The popularity of Conowingo Dam in winter illustrates
the attraction of birdwatching, even in the face of adversity. The best
times for viewing at the dam coincide with the dead of winter along a
river often churning from a bone-rattling wind. Yet only the worst of
winter conditions can keep the flocks of watchers from the flocks of
birds at Conowingo Dam.
Ad Crable is outdoors editor of the Lancaster New Era newspaper in Lancaster, Pennsylvania. He has written for Audubon, Field & Stream, and Backpacker magazines.||