HAWK, common name for many of the birds of prey of the family Accipitridae,
which also includes the eagles and kites, and the harriers, which have
often been
called "hawks." Members of the genus Buteo are called "hawks" in North
America
and "buzzards" in the Old World. In the Americas, some members of the related
family Falconidae have been called "hawks" in the past; the peregrine falcon,
for
example, was known as "duck hawk" and the merlin as "pigeon hawk." The
osprey
is commonly called "fish hawk." There is no clear-cut definition of just
what
constitutes a "hawk."
Sometimes called the "true hawks" are the 48 species of the genus Accipiter,
which
includes the goshawks and the sparrow hawks. Two North American representatives
of this group are the sharp-shinned hawk, A. striatus, and Cooper?s hawk,
A.
cooperii. Both are blue-gray above and mottled reddish brown below as adults,
brown above and streaked brown and white below when young. They differ
in details
of coloration, but chiefly in size; the sharp-shinned hawk is 25 to 36
cm (10 to 14 in)
long and the Cooper?s hawk 36 to 51 cm (14 to 20 in), females being the
larger sex
in both. These are the principal avian predators on small birds.
Most of the other North American hawks are members of the genus Buteo.
Other
genera include Buteogallus, the black hawks of the New World tropics, of
which one
species, the common black hawk, B. anthracinus, barely reaches north to
the
southwestern U.S., and Parabuteo, of which the single species P. unicinctus,
Harris?s hawk, is also primarily tropical but occurs north to central Texas.
It is
mostly dark brown, but with conspicuous chestnut shoulders and wing linings,
and
a white tail crossed with a broad black band.
All hawks feed on living prey, but tend to specialize partly based on size.
Thus the
smallest hawks feed primarily on insects, and the "bird hawks" of the genus
Accipiter choose their feathered prey in accordance with their own relative
size.
Some hawks prefer cold-blooded animals, such as amphibians and reptiles.
The
majority feed principally on appropriately sized mammals, although they
will take
other prey opportunistically.
Most hawks build bulky nests of twigs, bark, and leaves high in trees.
The eggs are
usually white or bluish white, variably blotched and spotted with shades
of brown.
The young are covered with white down, and are relatively helpless at hatching.
They grow slowly, and are dependent on their parents for food even after
they have
fledged.
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