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Biologists look for ways to make the bay a better home for ducks

Natural ResourcesBiologyUniversity of ConnecticutMichigan State UniversityU.S. Geological Survey

These are tough times for the ducks that winter on the Chesapeake Bay.

Threatened food sources and an imperiled habitat are forcing migrating waterfowl to look for other winter digs.

Alicia Berlin hopes to unlock the formula to win them back.

In a quiet corner of the Patuxent Wildlife Research Center in Laurel, the waterfowl biologist and her team are studying captive black ducks and scoters to find ways to make the bay more nurturing and learn more about the birds' time away from the Chesapeake.

"The number of ducks has been declining, and we need to understand why," Berlin said.

Black ducks, once numbering 200,000 on the bay, are down to 37,000. The scoter population, which comprises three types of birds, including surf scoters, is cyclical and has ranged from a high of 120,000 birds to a low of 5,000 birds over the last 50 years.

The black duck problem caught the attention of the Obama administration, which ordered an increase in the wintering population to 100,000 birds by 2025 as part of the Chesapeake Bay restoration plan.

Paul Peditto, director of the Maryland Department of Natural Resources' Wildlife and Heritage Service, said the strategy boils down to "Save the black duck, save the bay."

"The black duck will never wear the crown in a Chesapeake critter contest," Peditto said. "They lack the visual appeal of striped bass, the foodie fanfare of crabs or oysters and the spectacle of the canvasback. But restoring the black duck to 100,000 wintering birds will be a great step toward bringing back the bay — and securing the future for rockfish, crabs, oysters and all waterfowl that rely on a healthy bay watershed."

Home to 130 ducks representing 11 species, the Patuxent center, run by the U.S. Geological Survey, collects eggs in the wild and hand-raises the ducklings so scientists can study their habits. The captive colony of diving ducks and sea ducks includes surf scoters, white-winged scoters, long-tailed ducks, harlequin ducks and lesser scaup. Sixty-four enclosed ponds mimic conditions each species favors. Staff and volunteers tend the flock.

Berlin learned to raise waterfowl on the family homestead in Sykesville. A 1994 graduate of Garrison Forest School in Baltimore County, she received degrees from the University of Connecticut and Michigan State University before coming home to earn her doctorate — in ducks — from the University of Maryland.

For wild black ducks, also called dabblers, the danger is shrinking habitat, Berlin said. To that end, the Blackwater National Wildlife Refuge outside Cambridge has pledged to protect and restore wetlands and eliminate invasive species to increase food sources 10 percent by 2017. That program could be incorporated at other Chesapeake sanctuaries.

For scoters, called sea ducks, Berlin and her team are trying to solve a twofold mystery: figuring out migration routes to prevent wind farms from being built in their paths and learning if there's a replacement in the bay's pantry for the dwindling supply of their favorite feast, the hooked mussel.

The waterfowl team is placing $2,500 transmitters on the backs of surf scoters and tracing their routes between breeding grounds in northern Quebec and the Chesapeake to create "the best darn bird map on the East Coast," Berlin said.

The food issue is thornier. Scoters — surf, black and white-wing — view the hooked mussel as "a big Twinkie," packed with energy and easy pickings, said Berlin. Three quarters of the scoter's diet consists of the smaller mussels.

Hooked mussels, also called dark false mussels, are Chesapeake natives and especially abundant on oyster reefs. When oysters don't do well, the mussels don't, either.

In the absence of mussels, the ducks forage for hardier dwarf surf clams, which may not be as nutritious.

At the research center, scientists monitor feeding time. In two large glass-sided tanks, 8-feet deep and each holding 2,000 gallons, ducks dive and spin, air bubbles rising from their feathers as they dash for the bottom to feed on surf clams.

"We are studying what would happen if scoters had to switch to a diet consisting completely of surf clams," Berlin said. "Can they survive? Can they meet their daily energy needs?"

Berlin said the study might conclude that surf clams simply can't sustain a large wintering scoter population on the Chesapeake.

"But if they restore the oysters and restore the mussels, they will go a long way to restoring the scoter," she said.

candy.thomson@baltsun.com

Copyright © 2014, The Baltimore Sun
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Natural ResourcesBiologyUniversity of ConnecticutMichigan State UniversityU.S. Geological Survey
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