Biology Reference
In-Depth Information
In the water, Bufflehead Ducks raft to-
gether in groups to rest. In flight, Buffle-
heads can be recognized by their small
size, black-and-white feathers, and rapid
wing beats. (Norris R. Dyer)
their body weight in fat. Toward the end of this overwintering period, Buf-
fleheads begin to select mates, often staying with the same individual for
several years. To keep pair bonds strong, Buffleheads engage in year-round
courting behaviors involving flyovers and head shakes, wing lifts, and head
bobs, as well as a variety of squeaks, chatters, growls, and guttural rolls.
In San Francisco Bay, Buffleheads frequent marshes and salt ponds,
and they forage in waters less than ten feet deep during dives averaging
over 12 seconds in length. On the ground they look awkward, with feet set
seemingly too far back on their bodies. But in the air they fly faster than
most other waterfowl.
Great Blue Heron
The Great Blue Heron (
Ardea herodias
) is an elegant and powerful bird.
Like sharks and seals, Great Blue Herons are among the region's top preda-
tors. They have plenty of tools to accomplish their hunting tasks—tall,
slender legs for wading and long, sharp beaks for snapping up all manner
of prey. Anyone driving around the bay has seen the Great Egrets—
smaller, white-plumed relations of the Great Blue Heron—fishing on wet
highway verges. The heron is equally common around the bay, just less
visible against the brown-and-green backdrop of marshes, ponds, and
streams.
Great Blue Herons stand up to five feet tall. At least half of that height
consists of leg. In flight, their six-foot wingspan seems to flap in slow mo-
tion. But standing in the shallow tidal waters of the bay is where this bird
is in its element. Herons remain absolutely still to stalk prey—unlike
egrets, which tend to mince slowly along. A couple of uniquely flexible
vertebrae in a heron's long neck enable it to perform a slingshot maneuver
as it thrusts its bill out for unsuspecting fish, gophers, snakes, or frogs.
“The whole heron family is phenomenal in their ability to find good
places to stand,” says Audubon Canyon Ranch's John Kelly, author of an
atlas of egret and heron rookeries throughout the Bay Area. “They're really
adapted to foraging in places where water levels are receding, or in places
