American Kestrel

SCIENTIFIC NAME

Falco sparverius

CLASSIFICATION

Class:	Aves
Order:	Falconiformes
Family:	Falconidae
Genus:	Falco
Species:	sparverius

The American Kestrel was once known as the “Sparrowhawk”. Other nicknames include the Killy Hawk, the Wind Rover, and the Grasshopper Hawk.

SIZE

Length:	Male:	8 3/4-10 1/2 inches
	Female:	8 3/4-12 inches
Weight:	Male:	90-120 grams
	Female:	90-165 grams
Wingspan:	Male:	20-23 inches
	Female:	21-24 inches

APPEARANCE:

This falcon is one of the few birds of prey whose sex can be determined by coloration. The male has bluish-slate gray on top of his head with a chestnut crown and bluish-slate gray wings. The back is almost completely chestnut. They have a whitish breast, suffused with light amber-brown, and under parts spotted with black. The tail is red with a black sub-terminal band and white tip. The female’s back, wings, and tail are broadly barred with chestnut and dark brown. They lack the bluish-gray on the head and wings that the male has. The under parts are white streaked and barred on the flanks in cinnamon, along with a brown spotted breast and abdomen. Both have a black patch or stripe on their white face that extends from the eye to the throat with another across the ear. The beak is blue-black. The cere, legs, and feet are yellow to yellow-orange.

The juvenile is similar to the adult, but more spotted or barred. The juvenile male’s back is slightly darker and completely barred. The tail is tipped with ferruginous not white. The under parts are streaked and spotted throughout. The juvenile female has less conspicuous ferruginous streaking on the head. The back is darker with heavier black barring.

The American Kestrel keeps the juvenile wings, tail, and part of the body plumage through an incomplete molt starting in September or October of the first year. They do not lose these feathers until their second annual molt. At two years (or by the spring of their third year), the immature birds are indistinguishable from the adults.

RANGE/DISTRIBUTION:

American Kestrels are very widespread, ranging throughout the Western Hemisphere. They are found from above the Arctic Circle in Alaska and northwestern Canada, south through Canada and the United States, into Mexico, parts of Central America, and most of South America. The American Kestrel is the smallest and most common falcon in these areas.

HABITAT/TERRITORY SIZE:

American Kestrels occur in a variety of habitats from sea level or below up to about 12,000 ft. in the Rockies. They require open ground for hunting and are most often found in habitats such as mountain meadows, marshlands, grasslands, deserts, open pine forests, and any kind of mixed woods or grasslands, agricultural land, vacant sites, airfields, along the edge of highways, etc. American Kestrels usually defend a territory of approximately one-half square mile.

MIGRATION:

Those kestrels that are found in the northern range, above latitude 45 degrees north, are highly migratory. Those south of 35 degrees north are mostly year-round residents. In Oregon, American Kestrels are most abundant between March and September, although some are seen all year long.

DIET:

Prey consists mostly of small rodents, reptiles, insects, and an occasional small bird hence the common name of “Sparrowhawk. American Kestrels have been photographed killing prey as large as a wood rat!

HUNTING METHOD:

American Kestrels hunt by openly skimming over the countryside or “hovering” over a spot in a field waiting for their prey.

BREEDING INFORMATION:

Most do not gain access to a mate and nesting territory until they are two years old. Males tend to establish their nesting territory first, then the females join them. At first, the females are loosely bonded to a particular mate. They move about between two or more males before settling down with one. Kestrels prefer tree cavities as nest sites, but will also use potholes or crannies in a cliff, enclosed space in a building, or an abandoned nest from another bird. They will also readily accept nesting boxes. The availability of suitable tree cavities may be the chief density-limiting factor on breeding populations. Since they do not make their own holes, they depend on natural cavities or holes built by other birds; and, as a result they have to compete with woodpeckers, owls, squirrels, etc.

Courtship is simple and consists chiefly of aerial maneuvers and noisy cries by the male in the pursuit of the female. American Kestrels have been seen first to mate with the birds facing one another and slowly bobbing their heads and tails while the female keeps up a continuous low call. Courtship behavior usually begins with the onset of spring. After mating, the male brings the food to the female in the nest; and she begins to cache the extra. Depending on their range, eggs may be laid from mid-April through early June. The female can lay 3-7 buff, with reddish-brown, marked eggs but typically 4 or 5 are laid. Incubation lasts about 30 days, and the young begin to fledge at 27-34 days.

BEHAVIOR:

The cry of an American Kestrel is a fairly high pitched “qui, qui, qui” or a short, shrill chatter “ki-wee, ki-wee, ki-wee.”

American Kestrels are able to hover. Many birds can hover for a short period of time, but few can sustain it for long since it is an energy draining exercise. Prolonged hovering is mainly limited to specialists such as the kestrels of the Old and New Worlds. Like all falcons, American Kestrels have evolved for speed in flight and can dive at speeds of up to 65 m.p.h. To achieve this speed, its wings are slender and pointed and it is amazingly light, weighing only about 1/4 pound!

STATUS:

Although man is the biggest threat to kestrels, they could fall prey to a larger hawk or falcon and have even been killed by ravens on occasion. The domestic cat also poses a threat to these small birds. Crows and ravens are destructive to the eggs when left unprotected in the nest. In some areas, kestrels are losing their natural nesting sites such as cavities in trees, and may depend on nest boxes being placed in these areas.

FOLKLORE AND MYTHS:

Falconry became a serious sport in England in 1066. You could tell the rank of an Englishmen by the falcon he carried on his wrist. The Old World kestrel was carried by priests.

BIBLIOGRAPHY:

• “Birds of the Pacific Northwest”, by Ira N. Gabrielson and Stanley G. Jewett, 1970, Dover Publications, Inc., New York.

• “Birds of Prey”, by Philip Burton, 1989, Gallery Books, New York.

• “Birds of Prey of the World”, by Mary Louise Grossman and John Hamlet, 1964, Bonanza Books, New York.