Geographic range:
Nearctic: Distributed throughout North America. It breeds from
British Columbia east to New Foundland, and south to southern California,
Florida and the Gulf Coast. It winters north as far as southern Canada.
The common crow is a partial migrant but a permanent resident in some
areas. In Mexico it is resident to Baja California and in winter to
coastal Sonora.
Physical characteristics: Charcoal
black in color. It is approximately 42 -52 cm in length. A fan shaped
tail distinguishes the common crow from raven which has a wedged shaped
tail. Another feature of the common crow is its steady flapping flight,
which is different from the raven's soaring. These two species can
also be told apart by different vocalization.
Food habits: Omnivorous. Its diet
includes wild fruit, snails, salamanders, grain, small birds, mice,
eggs, toads, corn, large quantities of insects and carrion. Around
coastal areas, crows display behavior similar to that of gulls, picking
up clams and mussels and dropping them from heights to crack open
the shells. They then swoop down to ingest the soft contents. Adult
crows eat their weight in food every day, dividing the feedings between
eight to ten full meals.
Reproduction: Courtship of the common
crow takes place on the ground or in trees. It begins when the male
faces the female and fluffs its body feathers. Then he partially spreads
his wings and tail and proceeds to bow repeatedly while uttering a
brief rattling song. Once a male and female have mated, they perch
together and may touch bills and preen each other's feathers. Common
crows also demonstrate cooperative breeding. A breeding pair may have
a helper or helpers who aide them in all aspects of nesting. The helpers
and the mated pair participate in the parental duties of caring for
the offspring. Both males and females help in the construction of
nests, which are frequently placed in heights up to 75 feet; a common
location is the tops of trees. If trees are not available, they will
build a nest on the ground. The nest is typically 30 cm in diameter
and is made of twigs, grasses, and tree bark. Three to seven eggs
are laid by the female. The eggs are dull blue-green to grey-green
blotched with grey and brown markings. Both parents sit on the eggs
for an incubation period of eighteen days. The young are born blind
and flesh colored. After about five days, their eyes open for the
first time. At five weeks of age the fledglings are ready to make
their first flight.
Behavior: Very intelligent and adaptable
animal. In one word one could describe them as opportunistic. Recent
studies by ornithologists show that crows and ravens are among the
most intelligent birds, along with other members of the Corvidae.
Crows gather in groups from two to eight birds in the summer, while
during the winter they gather from many miles in great nocturnal roosts
of up to thousands of birds. During the day they fly up to fifty miles
away from these roosts in search of food. During feeding, one of two
crows can be seen on high perched places serving as a lookout for
the rest of the flock. These sentinels watch for signs of danger and
warn the rest of the flock. This behavior allows the rest of the flock
to forage more efficiently. The crow's call has variations that allow
it to express warning, threats, taunting, and cheer.
Habitat: Opportunist that has been able to occupy a number
of habitats, including coastal areas, towns, fields, and the edge
of forests. The Common Crow is found throughout North America except
in deserts, deep thickets, and on mountain tops. Its most common habitats
are woodlands, farms, fields, river groves, shores and towns.
Biomes: taiga, temperate forest &
rainforest, temperate grassland, chaparral, desert |
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