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Double-crested Cormorant
Common Name: Double-crested
Cormorant
Scientific Name: Phalacrocorax auritus
Description
Double-crested
Cormorants
are part of a world-wide order of seabirds
that includes pelicans, boobies, tropicbirds, and
frigatebirds. They are members of the family Phalacrocoracidae
and can be found throughout North America in both fresh water
and marine habitats. Double-crested, Red-faced, and
Pelagic cormorants are the only cormorants found
in Alaska. Cormorants dive underwater and use their large
webbed feet as paddles to swim in search of food.
Unlike
other seabirds, cormorants do not venture far from their nesting
colony. They build tall, stacked nests out of whatever plant
material they can find and are not above stealing it from
one of their unsuspecting neighbors. Often, one bird of the
pair will present a piece of grass or seaweed to
its mate as a way of strengthening their bond.
Diet
They
eat a wide variety of foods, but fish that live close to the
ocean floor are their favorites.
Characteristics
All
black feathers on entire body except for yellow bill. Thick
neck with hooked bill.
Size
Height:70-90
cm (28-35 in);
Weight: 1200-2500 g (42.36-88.25 ounces);
Life History
This
bird forages for fish, mostly by diving and being able to
stay underwater for about 30 seconds. It
tends to rest and roost on offshore cliffs and on rocks, wharfs,
and branches. It sometimes rests on water. Its takeoff is
quite laborious. The nests are quite sensitive to disturbance
and are found on rocky cliffs, slopes, and tall trees. Breeding
season runs from April to August. This species is monogamous
by nature and nests colonially.
Frequency
The
Double-crested Cormorantis common throughout
the year within the Presidio.
Identifying Characteristics
This
bird has the tendency to be an upright percher with a S-shaped
neck and hook-tipped bill. Unlike its relative, the Brandt's
Cormorant, this species displays an orange-yellow throat pouch.
These birds tend to cluster in silent flocks, forming in geese-like
patterns.
Distribution
 Unlike
the Pelagic and Red-faced cormorants, Double-crested's
are the least picky about where they build their nests, finding
comfortable spots Double-crested commoranton
vertical cliff faces, flat ground, and even in trees. Their
nests have to be large enough to hold up to four chicks, who
grow as large as their parents before they leave the nest
for good. Before the young cormorants fledge, they wander
from their nest to socialize with other young cormorants in
groups called creches.
For most of the year, cormorants wear a rather dull plumage.
When the breeding season approaches they dress -up in their
best outfits in hopes of attracting a mate. Their dusty gray-black
feathers take on an iridescence like that of pea-cock feathers,
although not quite as fancy. Depending on the light, their
dazzling plumage can look blue, green, purple, black, brown
or all of these at once. Double-crested Cormorants
grow long white tufts over their eyes before the breeding
season, and the skin around their bill and on their throat
turns bright Double-crested comorant yellow.
Cormorant feathers are unique compared to other diving birds
in that they are not naturally waterproof. As a result, they
spend a great deal of time spreading oil from a gland at the
base of their tail over their feathers to help keep themselves
dry and warm.
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