BIRDS
Status: Common, Native Summer Resident

SWAINSON'S HAWK
(Buteo swainsoni)

Description

Swainson's hawks are large birds of prey with a characteristic body common to other North American buteos. Buteos are
species of hawks with heavy bodies, short, wide tails, and long, broad wings. A Swainson's hawk is distinguished from most
other buteos in South Dakota by its long, narrow, and somewhat pointed wings, as seen in flight. A Swainson's is a stocky bird that averages 21 inches (53 cm) in length with a wingspan of over four feet (132 cm). 
 
Adult birds with light plumage are dark brown across the back and top surfaces of wings. The head displays a chocolate
brown hood and bib. A white face patch is noticeable below and slightly above the sharply hooked beak and may extend out
onto the eyebrows. Below the brown bib are contrasting cream to whitish-colored belly and legs. Light brown to cinnamon
streaking is apparent on the flanks. The tail is gray-brown with six narrow dark bands and a wider, dark subterminal band.
Possibly the simplest identifying feature of this species is displayed while the bird is in flight. On the underside of the wing,
the white to cream body color extends out onto the wing linings and creates a striking contrast to the very dark flight feathers.
All other buteos commonly found in South Dakota have light feathers. An adult hawk in its light plumage is easy to recognize.

The light-plumaged Swainson's hawk is the most common form, but the species also exhibits a dark phase throughout its
range. Dark phase adults are sooty brown all over except the tail, which is similar to the light phase. The bird's white throat
is a good field mark. Dark phase Swainson's lack the sharp contrast between wing lining and flight feathers on the underside
of the wing, as displayed in other dark phase hawks. Other dark phase buteos possess light flight feathers. Generally, a dark
bird with a noticeably lighter tail and dark underwings will be a dark phase Swainson's.
 
 
 
 Distribution

Swainson's hawks are common summer residents in South Dakota, found in large numbers throughout the central and western portions of the state. The birds prefer the large, open tracts of land found in shortgrass prairies and farmlands. Hawks begin arriving in the state from their wintering grounds in central to southern South America in late March.

Natural History

The Swainson's hawks arrive in South Dakota when the rough-legged hawks, which winter in the state, are departing for
their nesting grounds in the Arctic. The two hawks use the same habitats during different seasons. Swainson's hawks build
nests and raise their young within the state. Fall migration begins in late September with all of the birds gone from the state
by late October.

Swainson's hawks usually build their nests in trees located in creek bottoms or in isolated trees on grasslands. Often paired
birds will occupy the same nest site for successive years, each year adding more sticks and twigs to their flimsy platform
nest. Birds produce one brood per year, laying 2 to 4 eggs. The female provides security for the nest, while the male does
most of the hunting. Swainson's hawks prey on small mammals, birds, and large insects, commonly grasshoppers. This
behavior has earned this species the nickname "grasshopper hawk." The hawks hunt primarily from perches such as fence
posts and low trees, where they can rapidly pounce upon unsuspecting prey. Swainson's often soar over open plains and
prairie with uplifted wings in a teetering acrobatic flight. The shallow V formed by the wing position is a good field mark
for identification purposes.

Conservation Measures

Humans pose the greatest threats to Swainson's hawks and other birds of prey. Pesticides that people apply to control insects
are consumed in large quantities by the hawks when they feed upon abundant grasshoppers. Each year many hawks die due to
the build up of pesticide residues within their body tissues. Hawks are subjected yearly to illegal shootings by those who
believe the birds are a threat to livestock, and by unethical individuals who find the birds easy targets. Also, many birds die
from collisions with automobiles. These hawks commonly perch on fence lines searching for food. Often they feed on
mammals struck by vehicles. In most situations, the birds are not seen by drivers or the drivers assume the birds will fly
before their vehicle hits them. Many hawks, trying to defend their prey, are struck and killed in this way.

Laws currently exist to protect all birds of prey, but more effort is needed to correct the misinformation commonly believed
about these birds. The only sound conservation measure to protect our North American birds of prey is education. By
educating ourselves, we become more aware of the true role other fantastic creatures play in our environment. Often, an
appreciation for a specific animal is not found until the animal is threatened or endangered, when it could be too late.

References
 

Ehrlich, Paul R. et al. 1988. The Birders Handbook. New York: Simon & Schuester Inc.,
Field Guide to the Birds of North America, 2nd ed. 1987. Washington, D.C.: National Geographic Society.
Mansell, William. North American Birds of Prey. New York: William Morrow & Company, Inc., 1980.
Peterson, Roger T. A Field Guide to Western Birds, 2nd ed. 1961 Boston: Houghton Mifflin Company.
SDOU, The Birds of South Dakota, 2nd ed. , 1991. Aberdeen SD: NSU Press.
The Audubon Society Master Guide to Birding, 3 vol. 1983. New York: Alfred A. Knopf.
Welty, Joel C. The Life of Birds, 3rd ed. 1982. New York: Saunders College Publishing.

Selected Resources For Teachers
 

Birds of Prey Coloring Book, Dover Publications, 31 E. 2nd St., Mineola, NY 11501. 42 species illustrated.
Birds of Prey Poster , vol. I & II. Windsor/Nature Discovery, 1000 S. Bertlesen #14, Eugene OR. 97402. These are full
color, high quality posters with original artwork of hawks.
Birds of Prey Poster and Mobile set, Education Services, Division of Wildlife, S.D. Department Game, Fish and Parks,
3305 West South Street, Rapid City, SD 57702. This set includes a full color poster with hawk and owl pictures, plus a
mobile and fact sheets.
Birds of Prey Zoobook Series, Wildlife Education Ltd., 9820 Willow Creek Rd., Suite 300, San Diego, CA. 92131. ISBN:
0-937934-01-1.
Field Guide to the Birds of North America, 1987. The National Geographic Society, Easy to follow guide with great
illustrations.
North American Birds of Prey, 1980, a book by William Mansell, with artwork by Gary Low. An informative text with
beautiful paintings.

Written by:
Pat J. Buscher, Pierre, SD 57501. 1996.

Illustration by:
E.W. Steffen from the Birds of South Dakota with permission of the SDOU.

Reviewed by:
Dr. Dan Tallman, Northern State University, Aberdeen, SD 57401.

Publication of the Swainson's Hawk fact sheet was funded by the South Dakota Department of Game, Fish and Parks,
Division of Wildlife, Pierre, SD.