Description
& Characteristics:
The
Blue-eyed Shag, or Cormorant, is found on the western side
of the Antarctic Peninsula, the Scotia Arc, South Georgia
and the western coast of South America. They are the only
member of the Cormorants to venture down into the Antarctic
proper, with colonies found as far as 68 degrees south.
They are
unique among Antarctic and sub-antarctic birds in that they
will maintain a nest year-round where the sea is open and
they actively avoid pack ice. They were welcomed by the early
explorers and sealers because they never ventured far from
their nest site out to sea, and thus, were a sure sign of
approaching land.
Blue-eyed shags are characterized by a vivid blue eye color
and an orange/yellow growth at the base of their beaks that
becomes particularly large and bright during the breeding
season. They have a white-breast, a black back and largely
white cheeks and neck. The bill is dark brown and the feet
pink.
Blue-eyed
shags feed mainly on fish and invertebrates, often forming
dense "rafts" at sea of hundreds of birds that continuously
dive down onto the shoals below looking for fish. By fishing
in such large groups they help each other by panicking the
fish into having nowhere to go except into the beak of the
next bird. They are excellent divers with a recorded maximum
dive of 400 feet. Once underwater they are able use their
powerful webbed feet to propel themselves rapidly in search
of food.
The nests
of these gregarious birds are built on cliff tops close to
the ocean. The colonies can become quite raucous and lively
affairs, especially during the breeding season. Courtship
activities begin in late August to early October. Up to three
eggs are laid in October through to early January and these
hatch in November to February. Unlike other Antarctic birds,
Shag chicks are born "naked", meaning without any
down feathers. This makes them susceptible to extreme weather
and especially dependent on their parents when very young.
Fledging occurs in January to March, and the adults leave
the colonies in April.
The main
predators of Blue-eyed shags are the
sheathbill, which steals eggs from the nest, and leopard
seals, which attack the birds at sea.
Cormorants
do not seem to be under any current threat, however, but some
populations are so small (a few hundred pairs) that their
status needs monitoring.
