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Size and Weight: Harris' hawks are about 55 cm (22 inches)
in length with a wingspan of about 115 cm (45 inches). Their weight
ranges from about 700 gms (1.5 lbs) for a small male to over 1100
gms (2.4 lbs) for a large female.
Diet: The Harris' hawks diet includes small mammals, birds,
and lizards. They also catch desert jackrabbits, especially in
winter while hunting in cooperation. Jackrabbits are probably
hunted most commonly during short windows of time at dawn and
at dusk when the two species are both active at the same time.
Habitat and Distribution: Harris' hawks are typically
found in semi-dry deserts of southern Arizona, New Mexico, Texas
and Mexico. They prefer saguaros, mesquite, paloverde, ironwood,
cottonwood and riparian forests.
Status in the Wild: Harris' hawk populations seem to be stable
throughout their range.
Status in Captivity: ISIS (2002) indicates a World Captive population
of 213 birds and a North American population of 137. There are
no official programs for this species though they are readily
bred and flown by falconers throughout the United States.
Habits and Adaptations: Perhaps the most noteworthy aspect
of the Harris' hawk is their social structure. They have been
observed hunting in groups of 5-7 individuals and sharing the
rewards of the hunt. The extent to which this species hunts cooperatively
is still being investigated. It is possible that this behavior
occurs in certain populations driven by environmental circumstances.
They also have a curious habit of perching one on top of one another
on the saguaro cacti.
Breeding and Maturation: Harris' hawks typically make
a platform nest in the arms of the saguaro cacti. The breeding
pair is usually monogamous with one or more non-breeding helpers
although researchers have witnessed "every pair bond imaginable"
(Weidensaul, 1996). They may breed more than once per season and
the offspring may maintain a relationship with the parents for
several years. Two to four eggs are laid between March and June
with incubation (33-36 days) shared by both parents. Fledging
generally occurs at about 7-8 weeks.
Lifespan: The longevity record for a wild Harris' hawk
is 12 years. In captivity they can live into their 20's at least.
This species has a low juvenile mortality rate compared to other
raptors, possibly due to their communal hunting and shared parental
care.
Conservation Issues: Although their population seems to
be stable, the Harris' hawks desert habitat is being threatened
by development.
Bibliography
Brown, Leslie and Amadon, Dean. 1968. Eagles, Hawks and Falcons
of the World. Volumes 1 & 2. Country Life Books. Great Britain.
Burton, P. 1991. American Nature Guides. Gallery Books, New York.
Dunning, J. 1994. Secrets of the Nest: The family life of North
American birds. Houghton Mifflin Co. New York.
National Geographic Society. 1987. Field Guide to Birds of North
America, 2nd ed. National Geographic Society, Washington, DC.
Weidensaul, Scott. 1996. Raptors: The birds of prey. Lyons and
Burford, Publishers. New York.
Photo: by Dave Blom for the Minnesota Zoo
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