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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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