Winter Ducks on the Bay

Where Have all the Waterfowl Gone?

By Henry S. Parker

In the frigid mid-Winter, when it might seem that nothing could stir in the Chesapeake’s congealed waters, ducks bring life to the Bay. They’re active throughout the estuary in the Winter, from ice-free quiet coves to white-capped open waters. If you’d like to see for yourself, grab your binoculars and go exploring some cold, February day. With luck you’ll find buffleheads bobbing on the lower Patuxent, mergansers meandering through pancake ice at the Blackwater National Wildlife Refuge, scaup diving in the whitecaps off Sandy Point and surf scoters rafting up in Herring Bay. You may also find hunters who know that the coldest months are the best times to bag their limits.

About a million waterfowl spend the Winter on Chesapeake Bay—nearly one-third of all those migrating along the Atlantic Flyway. These include diving ducks, like redheads, canvasbacks, scaup and scoters; surface-feeders like teal and mallards; and geese. While a million birds may seem like a lot, that’s only a fraction of the numbers that historically stayed on at the Bay. In the mid-1800s populations began to plummet, primarily because of commercial hunting. The Migratory Bird Treaty Act of 1918 banned this practice, but the numbers never recovered from what they once had been. The reasons are complex. They have little to do with sports hunting and a lot to do with the distressingly poor health of the Bay.

Question: What time does a duck wake up?

Answer: At the quack of dawn.

Sorry, thought it was time for a little levity.

The simplest explanation for the declines in overwintering duck populations is insufficient food. But that needs some elaboration. Cold-season numbers of some waterfowl have substantially increased. Canada geese and mallards are examples. Their populations have swelled, in part because of hand-rearing and release of mallards for sport-shooting, and extensive grain production on the Eastern Shore, which benefits geese. Both species are now so numerous that they’ve become a problem and neither bird has to cope with food shortages. The geese have found good gleanings in Bay-area farm fields, and mallards can eat about anything.

On the other hand, some of the Chesapeake’s most emblematic ducks are finding it hard to sustain themselves. Black ducks are a good example. As recently as the 1950s, more than 200,000 overwintered on the Bay. Today that number is down to 37,000. The precipitous drop is due to a major reduction in their primary food source: submerged aquatic vegetation (SAV). SAV losses, in turn, result from deteriorating water quality.

Similarly, the numbers of redheads and canvasbacks now spending the Winter on the Bay have declined significantly since the 1950s, also because of SAV loss. Winter populations of redheads have dwindled from 70,000 to 2,000, while canvasbacks have diminished from 250,000 to 50,000.

A decline of food sources—SAV in particular—is not the only reason that Bay Winter duck populations have dropped. Other factors, including diseases, habitat degradation, competition with mallards and geese for space and resources, chemical contaminants, oil spills, predation on eggs and illegal hunting have also played a role. But the primary issue remains the loss of aquatic grasses from deteriorating water quality.

All is not lost, and there are signs of hope for Winter ducks on the Bay. Black ducks have recently received special attention, as scientists have concluded that remedial actions to restore this species will improve the environmental status of the Bay as a whole. Spurred by a Chesapeake Bay restoration goal of increasing overwintering populations to 100,000 black ducks by 2025, the Blackwater National Wildlife Refuge has committed to increasing aquatic food sources by 10 percent by 2017, through wetlands protection and expansion and elimination of invasive species.

Research is critically important. Ongoing studies that will help move Chesapeake Bay duck populations back toward historical levels include investigations of duck feeding behavior and migration patterns, habitat restoration, and SAV responses to water quality. Equally essential are efforts to expand public education, as the more we all know about these special birds and their importance to the Bay, the more likely we’ll make a strong commitment to protect them.

Now, how many ducks does it take to change a light bulb?

Henry is an adjunct associate professor at Georgetown University, He previously directed research programs at the U.S. Department of Agriculture and taught marine sciences at the University of Massachusetts Dartmouth. He can be reached at [email protected]

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