Classification and Range
They are found north to
southern Canada and south to almost the Sonoran desert. Northern populations
are migratory, while southern birds may remain within the breeding
range. As
much as 20% of the winter range may be in Mexico
Habitat
These buteos are restricted
to natural grasslands and shrub-steppe habitat. They prefer undisturbed
plains, high desert, sagebrush, or the edge of pinyon-juniper. |
Physical
Characteristics
These hawks are massive, long winged buteos that soar with wings held in a pronounced
V-shape known as a dihedral. They have a large head with a wide yellow gape.
There is a light and a dark morph, although dark birds make up a small proportion
of the population. The light plumaged birds have a whitish head and breast and
reddish-brown thighs. The upperparts are a mixture of blacks and browns with
rufous highlights. The unbanded tail is mostly white with shades of gray. Legs
are feathered to the toes. Dark birds vary, but are mostly dark with light-colored
flight feathers. Sexes are similar with females being larger. Wingspan ranges
from 48 to 60 inches (122-152 cm) and weights vary from 2.2 to 4.5 pounds (1-2.1
kg). |
Life
Span
A banded ferruginous hawk lived 20 years in the wild |
Diet
In the wild: Small and medium-sized mammals
make up 80-90% of their prey. Black-tailed jackrabbits, ground
squirrels and prairie dogs are some of the preferred items. Their
wide gape makes them uniquely suited for swallowing larger mammals
than other buteos. Some birds, reptiles and insects are also
taken.
At the zoo: At
the zoo: Rats, mice and quail |
Reproduction
Ferruginous hawks appear to be monogamous and pair bonds may be long
term. The pair may return to its territory year after year, and
they usually have several alternate nest sites. Choice of nest
site is limited in open country. Although adapted for ground nesting
they seem to prefer elevated nest sites, when available. These
sites include trees and shrubs, but cliffs, outcrops, utility structures
and provided platforms are used. Unlike most large raptors, ferruginous
hawks lay large clutches of two to six eggs. Incubation, mostly
by the female, lasts for about a month.
Life Cycle
Females brood the young for the first three weeks while the
male provides food for the family. Both sexes hunt after this. Young
begin leaving the nest in 38 days. Fledglings can kill prey soon after
leaving the nest, but tend to stay in the vicinity and remain dependent
for several more weeks. Adults will often leave their nesting territory
as soon as the young are catching prey. Mortality of juveniles is very
high due to starvation, collisions with power lines and other factors.
Open Country Hunters
Long, broad, relatively pointed wings for a buteo allow ferruginous hawks to
efficiently hunt their open habitats. They will often perch and wait for
prey on a raised perch, or on the ground at a small mammal burrow. Their
wing shape also allows them to hover, stationary in mid-air, searching
the ground below for prey. They share habitat with other raptors including
Swainson's and red-tailed hawks. They patrol their territories with high
circling flights.
|
Fascinating
Facts
- Winter roosts
of up to 24 ferruginous hawks have been noted around prairie
dog towns!
- The wide
gape of the ferruginous hawk is an adaptation for swallowing
large prey items, but may also assist in thermoregulation
in extreme heat by increasing the efficiency of panting!
|
A ferruginous
hawk can be seen at the zoo's Raptor Center. Other birds of prey
that can be viewed at the Raptor Center include the bald eagle, Harris's
hawk, turkey vulture as well as spectacled and barred owls. The Raptor
Center's Eagle Release Program has rehabilitated and released back
into the wild more than 80 eagles. The zoo's Raptor Center assisted
the Washington Department of Fish and Wildlife with a study to determine
the winter range of the state's ferruginous hawks. Satellite radio
transmitters were attached to birds from 1999 to 2002.
The ferruginous hawk's
long-term survival is threatened by two main factors. They are dependent
on natural grassland habitat, which is being converted to agricultural
use across their range. Equally important, the rangeland mammals
that they are specialized for preying upon are declining due to numerous
human-induced causes.
These hawks were petitioned for listing under the federal Endangered Species
Act in 1991, but were rejected. They are listed as threatened by several states,
including Washington, and are listed as endangered by Oregon. Although mainly
vulnerable due to habitat loss and degradation, shooting is still a factor, especially
during winter. Ferruginous hawks' shy and retiring nature often mandates the
use of fairly remote nest sites which are free of human disturbance. Protecting
and enhancing nesting areas, large open areas and maintaining prey populations
should help these birds survive. Artificial nest platforms have been used with
some success. More research is necessary to determine factors during winter and
migration that may influence long-term survival.
How You Can
Help!
Efforts to save threatened and endangered raptors require cooperation
and support at international, national, regional and individual
levels. You can help in this cause. Join and become active in Woodland
Park Zoo and other conservation organizations of your choice. Recycle
forest products. Eliminate or reduce pesticide use. Support breeding
programs for endangered birds of prey at zoos and other animal
care organizations. Let your elected representatives know your
views about the conservation of migratory birds and their wild
habitats.
Contact Woodland Park Zoo at webkeeper@zoo.org to find ways you can support conservation programs at the zoo.
Discover more about raptors by contacting the Peregrine Fund at
their Web site www.peregrinefund.org. Learn other ways
you can help conserve wildlife and their habitats by visiting our How You Can Help page.
Sources and
Suggested Reading
Bechard, M.J., and J.K. Schutz. 1995. Ferruginous Hawk (Buteo regalis).
In The Birds of North America, No. 172 (A. Poole and F. Gill, eds.). The
Academy of Natural Sciences, Philadelphia, and the American Ornithologists1
Union, Washington, DC. Weidensaul, Scott. 1996. Raptors: The Birds of Prey.
Lyons and Burford, Publishers, New York, NY. 382 p.
Johnsgard, Paul A.
1990. Hawks, Eagles, & Falcons of North America. Smithsonian
Institution, Washington, DC. 403 p.
Newton, Ian Dr. 1990. Birds
of Prey, Facts On File, Inc., New York, NY. 240 p.
Weidensaul,
Scott. 1996. Raptors: The Birds of Prey. Lyons & Burford,
Publishers, New York, NY. 382 p.
For Kids!
Burnie, David. 1988. Bird (Eyewitness Books). Alfred
A. Knopf, Inc., New York, NY. 64 p.
Zoobooks. 1986. Birds of Prey. Wildlife Education, Ltd., San Diego,
CA. 16 p.
More References
*
Taxonomic classification varies between references. Classification
information used in this fact sheet was taken from “A Complete Checklist of the Birds of the
World,” written by Richard Howard and Alick Moore. Second
Edition, 1991. |
Classification and Range
