Phalacrocorax auritus
Copyright, Dan Sudia
Double-crested Cormorants
are large birds, growing over two feet long, with a wingspan
of four feet. They are mostly black
with an orange throat. They have a long neck and webbed
feet. During breeding
season, males have two curly black crests on their
heads. Cormorants are water
birds, and are found at lakes,
rivers,
streams,
marshes,
bays, and coasts. They are great swimmers and divers, as
well as good flyers. Double-crested Cormorants
usually travel, feed, and roost
in groups. In breeding season,
cormorants gather in colonies
and build nests out of sticks, twigs,
feathers, grass, bark,
and trash. They have been known to also include pebbles and
parts of dead birds.
Copyright, Pedro Genaro
Rodriquez
Nests are built on the
ground, or in shrubs
or trees.
Female cormorants lay 3 to 5 bluish-green eggs.
Both parents care for eggs and chicks. Adults return from
feeding and regurgitate
(throw up) food into the chicks' mouths. Cormorants can fly about
6 weeks after hatching. Young cormorants gather in a group
called a "creche." They are browner in color than adults and
will get darker as they get older. Cormorants usually live
around 6 years, but can live much longer. Double-crested Cormorants
migrate
in Fall and Spring, though some are around in our area
year-round. Double-crested Cormorants
eat mostly fish. They dive underwater and hunt along the
bottom. They eat a great variety of fish species, as well as
other animals including: crayfish, shrimp, aquatic
insects,
amphibians
(such as tadpoles and newts), snails, mussels, and some
reptiles. Small fish are eaten
immediately. Larger fish are taken to the surface where the
cormorant flips it and swallows it head first. After feeding, cormorants
need to dry their wings. They do not have oil in their skin
to protect their feathers from getting wet, like ducks and
othe water birds do. Cormorants find a perch and stretch
their wings out until they are dry.
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Double-crested Cormorants often associate with other birds. Nests are built in trees alongside Great Blue Herons and other heron species. They will even use old heron nests as their own. Cormorants will feed with other water birds, such as gulls, ducks, and herons. These birds help each other with finding food and watching for predators. Predators of cormorant eggs and chicks include gulls, crows, Blue Jay, Common Grackle, Raccoon, Red Fox, and Coyote. Adult cormorants are preyed on by Bald Eagle and Great Horned Owl. When threatened, a Doulbe-crested Cormorant may vomit fish at a predator. |
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