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American Kestrel

Falco sparverius

American Kestrel

New York Status: Not Listed
Federal Status: Not Listed

Description

The American kestrel is the smallest and most widespread member of the falcon family. Adults have a body length of 20 to 27 cm (5-12 inches) and a wingspan of 50-61 cm (20-24 inches), that is, about the size of a Blue Jay. As with other raptors, the female is somewhat larger than the male; males typically weigh in at 80-105 grams (2.8-3.7 ounces), whereas females can weigh up to 120 grams (4.2 ounces).

The adult male has a reddish-brown back, slate blue or gray wings, a rufous breast and a white belly. The female differs by having mostly brown-streaked wings and a brown-streaked white or pale buff breast. Both sexes possess the dual vertical facial "sideburns" and ocelli markings (false eyes) on the back of the head and neck, which may be used to confuse predators. Kestrels have amazing vision and can detect an insect up to 100 feet away. They are often seen perched on roadside utility lines or hovering above fields in search of insects or small rodents. Frequently, they can be heard uttering their "killy-killy-killy" warning and territorial call.

Life History

American Kestrel Species Range Map

In our area, American Kestrels begin to pair up in late March or early April. Males arrive in breeding grounds first and perform elaborate diving displays to declare their territory and attract mates. Once a strong, often permanent, pair bond is formed, the male searches for appropriate tree cavities for nesting and present them to the female, who inspects them and makes the final selection. American Kestrels appear to favor woodpecker-excavated cavities in isolated dead trees in the middle of large grasslands, but they will also nest in the edges of the woods, natural and man-made crevices, and nest boxes. Females typically lay four or five pale, rounded eggs but as many as seven have been recorded. The nest is but a shallow scrape within the selected cavity. Eggs are lain at 2-3 day intervals, incubated mostly by the female, and hatch in about 30 days. During this time, the male brings food to his mate, an activity that continues after the eggs hatch. The young are born blind with scant white down covering pale pink skin and unable to feed themselves. Nestlings grow quickly, becoming downier. The eyes open by the second or third day, after about 20 days, they begin to feed themselves, and after about 30 days their wings are fully developed and they can fledge out of the nest. Family groups can be seen hunting together for the first weeks.

Distribution and Habitat

American Kestrels have a very widespread distribution, breeding throughout most of North America primarily south of the Arctic Circle, down into Central America, the Caribbean, and parts of South America in zones where appropriate cavities are available for nesting. Seventeen subspecies are currently recognized. In New York, they breed throughout, except for the Adirondacks, Tug Hill, and parts of the Catskill and Alleghany mountains. They prefer open habitats such as pastures, fallow fields, and grasslands, where they can find abundant insect or other arthropod prey. New York birds migrate south in the fall. Wintering grounds resemble breeding grounds. When insects are not available, they prey on smaller birds (hence the name Sparrowhawk, as they were once known), rodents, or even frogs and reptiles.

Status

Despite their distribution and relative abundance throughout much of the eastern United States, Kestrel numbers have significantly and steadily declined in the past fifty years, particularly in the Northeast. Regions surrounding the Adirondack, Allegany, and Catskills mountains, as well as suburban areas of the lower Hudson Valley and Long Island have experienced the greatest declines. The Second Atlas of Breeding Birds in New York State, (McGowan, K. J. and K. Corwin, Eds, 2008) reported an overall decline of 14% in the number of atlas blocks where American Kestrels were detected breeding. This decline is consistent with that of other birds requiring open grassland habitat. These important habitats are disappearing and becoming fragmented due to development, intensive agriculture, and plant succession.

American Kestrel Breeding Bird Atlas Maps

Human causes of mortality account for 43 % of reported deaths. A significant number of reported deaths, nearly 12%, occur from collisions with vehicles. This number can be expected to rise with increased miles of roads and highways and increased travel speeds. Shooting, trapping, and direct killing account for nearly 9% of deaths reported. Bioaccumulation of pesticides and other contaminants may be affecting reproduction. Competition for nests by European Starlings and other aggressive birds limits available nesting sites. Natural sources of mortality include parasitism, predation, and inclement weather during migrations.

Management and Research Needs

As a species that relies on grasslands and other open habitats, the fate of the American Kestrel is tied to that of other grassland birds. Since the majority of this habitat, well over 95 %, occurs on private lands, conservation and management of farmland and formerly agricultural land is vital to their long-term survival. State and Federal agencies and Non-Governmental Organizations (NGOs), and private landowners are participating on several initiatives to conserve and manage grassland habitat. One such conservation effort is New York's Landowner Incentive Program for Grassland Protection and Management.

The Peregrine Fund's American Kestrel Partnership has been actively studying the breeding ecology and factors influencing the decline of the species. Private landowners and the NYSDEC have been participating in this partnership by installing and monitoring nest boxes.

Additional References

Peterson, Roger T., 2002. Birds of Eastern and Central North America, Fifth Edition, Houghton Mifflin Harcourt, Boston, MA.

Baicich, Paul J. and Colin J. O. Harrison, 1997. A Guide to the Nests, Eggs, and Nestlings of North American Birds, Second Edition. Academic Press, San Diego, CA.

Smallwood, John A. and David M. Bird. 2002. American Kestrel (Falco sparverius), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/602 doi:10.2173/bna.602

North American Bird Conservation Initiative, U.S. Committee, 2011. The State of the Birds 2011 Report on Public Lands and Waters. U.S. Department of the Interior: Washington, DC

Smith, C.R. 1997. Use of public grazing lands by Henslow's Sparrows, Grasshopper Sparrows, and associated grassland species in central New York State. Pages 171-186 in Grasslands of northeastern North America: ecology and conservation of native and agricultural landscapes (P.D. Vickery and P.W. Dunwiddie, Eds.). Massachusetts Audubon Society, Lincoln, MA.

Nye, P. E. 2008. American Kestrel. Falco sparverius. Pages 206-207 in McGowan, K. J. and K. Corwin, Eds. The Second Atlas of Breeding Birds in New York State. Cornell Univ. Press, Ithaca, NY.

USGS Patuxent Wildlife Research Center. 2011. Longevity Records of North American Birds.