Episode 43
Copyright © John Page Williams, Jr. all rights reserved.
This is John Page Williams with another reading from "Chesapeake Almanac." The month is February and this chapter is entitled "Sea Ducks Relish Winter on the Chesapeake."
The open Chesapeake Bay is not a hospitable place in February. Most of the month is bitter cold. Strong winds and snow storms are always possible. On the surface of the Bay, only oystermen, a few hard-clammers in Virginia, and commercial shipping interests are active. Most animals are absent or dormant. It's a surprise, then, that in this otherwise desolate scene, that we find a group of ducks who seem to thrive on February's freezing temperatures and nasty weather.
The waterfowl include the long-tail and three species of scoter: black, surf ,and white-winged. The four are related and all adapted to cold open waters. They make remarkably long migrations to spend the winter here on the Chesapeake.
The birds summer breeding grounds are particularly striking to the imagination. The long-tails, formerly known as oldsquaws, that winter, say, around Hackett's Bar off Annapolis, may have come from the tundra of Alaska's North Slope, Canada's Arctic coast, or Greenland. Black scoters around Great Fox Island and Tangier Sound have come from ponds in the forests of western Alaska, Labrador, and Newfoundland. Surf scoters around Smith Point Light and off the Bayshore of the Northern Neck have come from glacial lakes in Alaska and northern Canada. White-winged scoters off Lynnhaven, around the Bay Bridge Tunnel, have likewise come from lakes in Alaska and Canada, though a few may breed as far south as North Dakota. All of these areas produce heavy summer crops of aquatic insects whose larvae provide essential protein sources for fast-growing ducklings.
If insect hatches in the high Arctic summer provide one essential dimension to the lives of these sea ducks, the Chesapeake's relatively shallow and at least generally ice-free waters with historically broad expanses of "live bottom" oyster rocks give them the other. The shallow waters (remember, the average depth in the Bay is only 21 feet) mean that they do not have to dive great distances to pick up food. The abundance of life on the bottom in this rich estuary provides them with a fine food source, mostly mussels and other small shellfish that live attached to shells and other hard bottom areas.
Each of the four sea duck species differs slightly in food preferences, but it is easy enough to draw some general observations about their way of life. They're heavily insulated against cold water, they dive to catch the food from the bottom, and they're capable of crushing shellfish as they eat them. Let's look at each set of features in turn.
Body heat conservation is a critical element in the sea ducks' design. All four species have compact, stocky bodies to minimize surface area through which to lose warmth. Plenty of downy under-feathers provide insulation and are covered by tough outer feathers that act as foul weather gear. The birds "waterproof" these surface feathers by preening, or rubbing the edges of their bills over them. This grooming behavior keeps the feathers properly arranged and allows the ducks to pick up oil from the preen glands at the base of their tails and spread it as additional waterproofing on the feathers.
The main design feature for diving is placement of the legs far back on the body, a characteristic which these sea ducks share with other diving waterfowl, like loons and cormorants. It gives them great power underwater. In addition, the long-tail and the white-winged scoters use their wings for propulsion underwater, and the other two scoters open them slightly to steer. The long-tail is the champion diver, capable of reaching depths in excess of 150 feet, though such dives are undertaken only in extreme need. It's very much to all four species' advantage to conserve energy by diving only short distances whenever possible.
Once the birds dive to the bottom, their stout bills allow them to nibble and tug at mussels and barnacles they find on oyster rocks and to root on the bottom for small clams. Once food articles are dislodged, the birds can swallow them and crush them in their muscular gizzards. They may also eat worms, small crabs, grass shrimp, and other tiny crustaceans that they find in the oyster communities.
Sea ducks have been coming to the Chesapeake for thousands of years. For most of that time, the Bay offered them extensive oyster rocks with plenty of food. As water quality in the Bay began to decline earlier in the past century, other waterfowl species like canvasback began to lose the submerged aquatic vegetation upon which they depend, but the sea ducks still had plenty of oyster bottom and clam beds. Now the precipitous decline of the Chesapeake's oyster stocks is taking a source of food away from them, though restoration is beginning to improve that and areas with rocky bottom, generally places like the Bay Bridge Tunnel, do offer them some food sources, as well.
The sea ducks are not in crisis; the numbers are declined only slowly over the 20th century. Still, there's concern for them, and any efforts we're able to mount to restore our Bay's oysters will benefit them greatly. The long-tail and the scoters are tough, competent ducks. Any bird that thrives on the open Chesapeake in February deserves our respect.
For more happenings around the Bay in February see our other Chesapeake Almanac podcasts and read our blog posts "Skunk Cabbage are the Bay's Bouqet" and "Great Blue Herons Prepare for Spring in February."
