ID Keys: Dark sooty-brown overall with obvious white rump patch,
paler upper-wing coverts, dark legs, dark feet with yellow webbing
The
Wilson's Storm-Petrel is one of the most abundant birds in the North
Atlantic during the northern Hemisphere summer. However, they are very
long distance migrants in the region, as their breeding grounds are found on
Antarctica and some far southern islands near South America. Truly
pelagic in nature, the small birds are tougher than they appear, as outside
of the breeding season, they spend their entire lives on the open ocean.
They are only rarely sighted from land, and usually only when storm events
push the birds closer to shore.
Habitat
Found in the open ocean from the freezing
waters at the edges of the Arctic and Antarctic ice pack, to the warm waters
of the tropics. They breed on the continent of Antarctica itself, as
well as a number of island groups in the far southern oceans.
Diet
Feeds on small crustaceans and small fish,
as well as marine worms, small squid, and carrion. They will follow
fishing vessels for discarded fish material.
Behavior
Feeds in the manner of other
Storm-Petrels, with a "foot-pattering" as they hover on the ocean's surface,
pattering their feet on the water and grabbing food items with their bill.
They will also sometimes forage by swimming on the ocean's surface and
directly grabbing food items when spotted.
Nesting
The Wilson's Storm-Petrel breeds in
colonies starting in November or December. The nest consists of a
crevice or cavity in rocks, on a cliff, or in a burrow in the ground.
Only one egg is laid, and both the male and female help to incubate it.
Upon hatching, the young is tended to and fed by both parents.
Song
Usually silent at sea away from breeding
colonies.
Migration
Very long-distance migrants, breeding
in the far southern oceans, but with non-breeding birds migrating in very
large numbers to the North Atlantic. Their status in the North Pacific is
less known, but they have been increasingly found on pelagic birding tours
that go far out from the coast of California.
