Geoscience Reference
In-Depth Information
Delaware Bay is a very important wintering area for waterfowl such as these long-tailed, or oldsquaw, ducks.
For some species—especially wading birds and waterfowl—the coast may in fact function as a leading line
that offers ample and familiar food supplies. And even for some songbirds the rich mosaic of coastal habitats
may also be attractive, and in turn, the presence of these prey species acts as a magnet for raptors. However,
the Cape May Peninsula of Delaware Bay and the Cape Charles Peninsula, which forms the north shore of
Chesapeake Bay, become bottlenecks where this aerial river of southerly flowing birds slows and pauses be-
fore moving on. Land runs out at Cape May Point and birds must decide to fly over water, a distance of 17.5
kilometers (11.5 miles), or go around the bay, a diversion that, though less fraught with immediate risk, is nev-
ertheless energetically costly. Cape May acts as a classic migrant trap, or bottleneck, where birds stop to refuel
and to determine their migratory strategy.
The region around Cape May offers a diversity of habitat types, from oceanic waters to bays to salt marshes,
and a little way inland, brackish marshes, freshwater lakes and ponds, and woodlands and fields. Birds pile up
here before moving on, in the interim replenishing their depleted fuel supply. But many species also find this
point, roughly midway between the far north and the deep south, a good place to stop and spend the winter,
and large numbers of waterfowl pass the cold months at the mouth of Delaware Bay and in the many back
bays along the New Jersey coast. Waters usually remain open in this marine-moderated region, making it a
stronghold for American black ducks as well as brant. New Jersey hosts about 70 percent of the 140,000 brant
that are estimated to comprise the Atlantic population. They arrive in mid-October and are among the last wa-
terfowl to leave, fattening on sea lettuce in New Jersey's back bays for their long flight to James Bay, where
they fuel up for the last leg of their journey to breeding grounds around northern Hudson Bay and Baffin Is-
land. Greater scaup, red-breasted merganser, and bufflehead also flock to the back bay lagoons in the lee of the
barrier islands for the winter.
