| Harris's
Hawk |
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Harris's
Hawk (Parabuteo unicinctus)
By James T. Driscoll, Nongame Biologist |
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Scientific
Name:
Parabuteo unicinctus. Para is Greek meaning near and buteo is Latin meaning
hawk. Unicinctus is Latin for once girdled, referring to the tail's terminal
band. Named after Edward Harris, this bird is also called the bay-winged
hawk. |
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Description:
Harris's hawks range from 18 to 23 inches in length, with a wingspan of
40 to 47 inches. The female (2.2 lbs) is larger than the male (1.5
lbs). Adult plumage is dark brown with brownish-red shoulders, leg
feathers, and wing coverts. The tail is dark brown with white upper
tail coverts, base, and terminal band. The beak, face, cere, and legs
are yellow in color. Immatures have a streaked breast with barring
on the wings and tail. Color markings on the shoulder, terminal band,
and base of the tail are less distinct. |
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Habitat:
Harris's hawks are associated with saguaro, paloverde, and ironwood dominated
desertscrub, semi-desert prairies, and cottonwood-mesquite forests.
In urban environments, they take advantage of washes, vacant lots,
and undeveloped desert. |
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Distribution:
Historically, Harris's hawks were distributed from San Diego, California,
east to Louisiana, and into Central and South America. In North America,
they now occur from Blythe, California, east through central and southern
Arizona, southeastern New Mexico, and southern Texas. Infrequently,
they occur in Kansas, Louisiana, Colorado, Utah, and Nevada.
In Arizona, most Harris's hawks occur in the Sonoran Desert south of Wickenburg,
Carefree, and Superior. Populations have largely disappeared from Organ
Pipe Cactus National Monument, the upper San Pedro River, Gila River between
Sacaton and Florence, and the Santa Cruz River south of Tucson. By 1969,
this species was extirpated along the lower Colorado River due to flood
control dams, dredging, agriculture, and recreation. In recent years, the
Harris's hawk's range has expanded near Tucson and now includes Wickenburg
and the Sulphur Springs Valley. |
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Biology:
Harris's hawk nests are usually placed in saguaros, mesquites, and paloverdes.
Urban nests are placed in cottonwood, pine, and palm trees and on transmission
towers. Most breeding females lay their first clutch of three to five
eggs by March. In good habitat, Harris's hawks can breed year-round
by laying two to three clutches. Incubation lasts 33 to 36 days; nestlings
fledge 40 days after hatching. Helpers (siblings and other group members)
improve nest success by participating in nest building, incubation,
feeding, nest defense, and prey deliveries to the young.
Harris's hawks use cooperative hunting techniques to catch prey. A family
group breaks into smaller groups that make "leap frog" flights. If the
prey is in the open, the smaller group makes the kill. Otherwise, one or
two hawks land and pursue it while the others wait in ambush. If the prey
does not come out, individuals will stoop on it, "herding" it toward the
other members. |
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Status:
Harris's hawks are not included on the Department's list of Wildlife of
Special Concern in Arizona (AGFD in prep.) and are not listed or proposed
by the U.S. Fish and Wildlife Service as threatened or endangered.
However, the Migratory Bird Treaty Act protects the species from harassment
and illegal shooting. |
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Management
Needs:
Because Harris's hawks in Arizona are primarily restricted to the Sonoran
Desert, development of natural areas for real estate and agriculture is
the biggest threat to the population. From 1957 to 1984, a 68 percent population
decline in Texas was attributed to mesquite clearing for agriculture and
livestock grazing. In Arizona, however, desert areas favored by this bird
and the burgeoning metropolises of Phoenix and Tucson can provide homes
for both humans and Harris's hawks if the native vegetation is adequately
protected, houses are not placed too close to each other, and asphalt and
concrete don't cover too much of the land surface.
Public education and appreciation would also help. Human disturbance and
shooting can cause adults to flush, nests to fail, family groups to abandon
the nest area, or direct mortality. In Tucson, electrocution caused the
death of nearly 50 percent (n=112) of breeding Harris's hawks. Insulating
poles, transformers, and wires, and installing perch arms will reduce mortalities.
Temporary closures and/or educational signs would also help nesting hawks. |
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