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 The
Chesapeake Bay is located along the Atlantic flyway, which every year
channels the annual seasonal flights of millions of migratory birds.
The region has always been a favored winter residence or stopover for
many species of waterfowl on their way south from their summer breeding
grounds. The shallow waters and wetlands of the Bay and its temperate
climate offer a fertile and diverse environment for waterfowl.
Waterfowl were once so abundant that they seemed to
blanket areas of the Bay and to "blacken the sky." Today their
numbers are greatly reduced. The deterioration of their shallow water
habitats, coupled with human activities, loss of wetlands in the US
and Canada have reduced the area’s capacity to support huge populations
of these migratory birds.
Habitat and Characteristics
Chesapeake Bay waterfowl fall into four categories:
dabbling ducks, diving ducks, geese
and swans. All have webbed feet, short legs and most
have wide, flattened bills. They migrate seasonally and depend on agricultural
areas, bay bottoms and wetlands for food and nesting habitat.
Each group has physical adaptations that are tailored
to the birds’ specific behavior and habitat requirements.
- Diving ducks, such as canvasbacks and redheads, have
legs that are situated far back under their bodies, which permits
them to dive deep in search of food but makes it awkward for them
to walk on land.
- Dabblers, such as mallards and black ducks, have
legs situated closer to the middle of their bodies, which enables
them to walk easily but inhibits their diving ability. They feed in
the shallows and can take flight without a running start.
- Canada geese are the most abundant waterfowl wintering
in the Bay area. Other geese in this family include snow geese and
brant. Each species has specialized bills for consuming agricultural
plants, submerged aquatic vegetation
(SAV), and other vegetation. With the decline of SAV in the Bay,
Canada and snow geese now rely heavily on grain left in agricultural
fields for food.
- The native tundra swan relies on the Bay only for
its winter habitat. Along with the less numerous, introduced mute
swan
 ,
it relies on SAV, and when SAV is scant, feeds instead on leftover
grain.
Duck Species
- The black duck and mallard are the most abundant
dabbling ducks in the Bay. However, while the mallard population is
increasing, black ducks are declining, apparently because they have
not been as successful in adapting to human interference. They raise
their broods in SAV beds, emergent marshes, beaver ponds rich in SAV
and insects and require that their brood-rearing and nesting habitats
be closely situated. Development throughout the watershed has affected
the areas where these habitats co-occur. This limitation, in addition
to the ducks’ intolerance to human disturbance, is contributing
to their decline in the Bay area.
- Mallards prefer similar nesting habitat to the black
duck, but the majority of resident Chesapeake Bay mallards are semi-domesticated
and often are seen near houses, marinas and areas of intense human
use. Resident mallards may adversely affect black duck populations
by competing for nest sites and food, or through hybridization with
black ducks. Increasing mallard populations may be a sign of degradation
rather than improvement.
- The canvasback is the most abundant diving duck found
in the Chesapeake Bay region. At one time canvasbacks consumed wild
celery almost exclusively. The sharp decline in wild celery caused
canvasbacks to shift their diet to small clams.
- The redhead, a close relative, continues to feed
almost exclusively on SAV, and has not been as successful in adapting
its feeding habits to the loss of its food source in the Bay. Only
small numbers of redheads now use the Bay for habitat and breeding.
Some species of waterfowl migrate for 3,000 miles, at
speeds of 40 to 60 miles an hour. Canvasbacks have been reported to
fly at speeds of 72 miles per hour.
It is estimated that at one time, millions of waterfowl
spent their winters in the Bay region, supported by profuse SAV beds
and supplemental diets rich in invertebrates. The destruction of wetlands
and dramatic declines in SAV, and water quality, human interaction,
overhunting, and poaching have reduced the number of waterfowl in the
Bay area to about one million birds.
This estimate may be deceptive, however. Not all species
of waterfowl have decreased over the past several decades. Some, such
as Canada and snow geese, have generally increased because they have
adapted their diets. Other populations, such as the redhead, scoters,
and old squaw have deteriorated which has resulted in a net reduction
in waterfowl numbers.
To bookmark this
page, please use this URL:
http://www.chesapeakebay.net/waterfowl.htm
For more information, contact the Chesapeake
Bay Program Office:
410 Severn Avenue, Suite 109, Annapolis, MD 21403 / Tel: (800)
YOUR-BAY / Fax: (410) 267-5777.
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Last modified:
4/7/04
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