American Kestrel

Photo Credit: Don Getty
http://www.dongettyphoto.com/

SCIENTIFIC NAME: Falco sparverius
 
OTHER NAMES: American Sparrow Hawk; Grasshopper Hawk; Rusty-crowned Falcon.
 
DESCRIPTION: The American kestrel is the smallest North American falcon and ranges from eight to 11 inches in length. Both sexes are very colorful and distinctly marked. The adult male’s head is topped with a cinnamon brown crown that is encircled about the head to the level of the eye with bluish gray. The throat and sides of the head are white with a black streak below the eye and a black border at the back of the white on the sides of the head.  The back is darker brown with evenly spaced black barring. The wings and wing coverts are slate gray with wedge shaped spots of black. The tips of the primaries have a yellowish tint. The breast and upper abdomen is light tan with the lower parts having black spots. The lower abdomen is white. The central tail feathers are rufous. The outer tail feathers are white with black bars. All of the tail feathers have a distinct black band near the end and are tipped in white. The thighs are feathered in white. The lower legs and feet are covered with yellow scales. The talons are black. The adult female is marked similar to the male with the following exceptions. The wing coverts will be rufous instead of grayish. The tail will have some pale barring on the upper shafts.
 
DISTRIBUTION: The American kestrel is widely distributed and abundant over much of its range. It is found in all of the contiguous 48 states northward into western Canada to southern Alaska. It ranges south through Mexico, Central America and South America.
 
HABITAT: The American kestrel’s natural habitat is open land including fields, meadows, pastures, prairies, and deserts. It is sometime seen in towns, but rarely in cities. It is seldom seen in the interior of a forest.
 
FEEDING HABITS: The American kestrel employs two types of feeding techniques. The most common is to remain perched in a location that provides a good view of the surrounding landscape and watch for prey. At other times kestrels will face into the wind and hover by flapping its wings as it surveys the terrain below. Its eyesight has been estimated to be approximately eight times stronger than humans. When prey is spotted it attacks by partially folding its wings making a swooping dive. Just before impact it will spread its wings and tail to brake grasping the quarry in its talons. American kestrels employ a kicking motion as it seizes its prey, which serves to increase the velocity of the actual attack, making it more lethal. Kestrels will return to their perch to consume their prey. The kestrel is considered an opportunistic feeder. It will eat what ever is easily caught. This includes crickets, beetles, grasshoppers and other insects, small reptiles or amphibians, mice, voles, or rats and small birds. Researchers have discovered that the young of other birds appear to be the choice food for feeding fledging kestrels. At other times during the warm months insects and mice are key food items. During the winter their diet is predominately small rodents. The kestrel’s diet benefits humans because it utilizes insects and small rodents that are generally destructive.
 
LIFE HISTORY AND ECOLOGY: American kestrels begin pairing for mating in February in the southern states, around April in the middle states and progressively later as latitude increases. Kestrels in the southern states usually raise two sets of young per year, while those in the more northern latitudes only attempt one nest. Courtship behaviors include mutual preening while perched, touching of bills, and nibbling the mate’s toes. Kestrels also engage in courtship flights or chases where they touch bills and grasp feet while in flight. Sometimes they will fly circles around each other. The female also does a flutter glide that stimulates the male to offer her food. During courtship they can be heard making the call kille, kille, kille.
 
The male takes on the responsibility of locating a suitable nesting site. American kestrels are cavity nesters. Suitable nesting locations include natural cavities in trees, abandoned woodpecker holes, niches in cliffs, or holes in the walls of deserted buildings. Nest boxes that are built especially for kestrels are eagerly used. The dimensions suitable for a kestrel nest box are one foot deep and wide with a height of 14 to 16 inches.  A four inch, round hole should be placed 8 to 12 inches above the floor of the box. Slight spaces should be left between the top and the sides to improve ventilation. Some small holes drilled in the bottom will allow for drainage. Sawdust in the bottom will give the hen a soft place to lay her eggs.
 
Once the male locates a prospective nesting site, the female inspects and approves the site before egg laying begins. Once laying commences, females will lay one egg, on approximately alternate days until a clutch of four to six eggs is completed. Kestrel eggs are round, pale brownish in color with darker brown and black splotches. Both the male and the female will incubate the eggs, alternately taking turns, feeding each other and watching for danger. Kestrels establish a territory around the nest of approximately one-half square mile. If intruders enter the territory the kestrel will pursue them screaming kille, kille, kille. Eggs are incubated for approximately one month before hatching. The parents feed and care for the young for another month until they fledge. After the young kestrels leave the nest, they remain with the parents for up to another month. They hunt as a family unit, each taking a perch around a field to watch for prey. Kestrels form such an attraction for a favorable perch that they may use it for months. Many Kestrels migrate south for the colder months; however some have been know to winter in the northern United States. Those that remain in the northern latitudes for the winter are usually associated with an agricultural setting.
 
 
REFERENCES:
 
Audubon Society, An online site with extensive information about birds. Accessed 5/4/06 at http://www.audubon.org.
 
Brown, Leslie, 1977. Birds of Prey Their Biology and Ecology, A&W Publishers, Inc. PUBLISHER, New York. Pages 125, 192-193.
 
Cruickshank, Allan D. and Helen G. Cruickshank, 1976. 1001 Questions Answered about Birds, Dover Publications, Inc. Pages 127, 169, 170, 231, 232, 234 and 235.
 
Grossman, Mary Louise and John Hamlet, 1964. Birds of Prey of the World, Bonanza Books, New York, Pages 101, 104, 125, 400, 407 and 408.
 
Heintzelman, Donald S. 1979. Hawks and Owls of North America, Universe Books New York, New York, Pages 87, 89, 90, 122, 123, 161, 165 and 172.
 
Pearson, T. Gilbert, Editor, 1936. Birds of America, Doubleday and Company, Garden City, New York. Pages 90-91.
 
AUTHOR: Steve Bryant, Wildlife Biologist, Alabama Division of Wildlife and Freshwater Fisheries

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