New York Status: Not Listed
Federal Status: Not Listed
The American Kestrel is the smallest and most widespread member of the falcon family. Adults have a body length of 5-12 inches and a wingspan of 20-24 inches (about the size of a Blue Jay). As with other raptors, the female is somewhat larger than the male; males typically weigh in at 2.8-3.7 ounces, whereas females can weigh up to 4.2 ounces.
The adult male has a reddish-brown back, slate blue or gray wings, a reddish-brown breast and a white belly. The female differs with 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. Ocelli markings 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.
In New York, American Kestrels begin pairing up in late March to early April. Males arrive in breeding grounds first and perform elaborate diving displays to declare their territory and attract mates. Once a pair bond is formed, the male searches for appropriate tree cavities for nesting and presents them to the female, who inspects them and makes the final selection. American Kestrels appear to favor woodpecker-excavated cavities in isolated dead trees located in the middle of large grasslands; however, they will also nest in the edges of woods, natural or 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 laid 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. They breed throughout majority of North America, primarily south of the Arctic Circle, down into Central America and the Caribbean, as well as parts of South America. They specifically target zones where appropriate cavities are available for nesting. Seventeen subspecies are currently recognized. They breed throughout New York State, aside from the Adirondacks, Tug Hill, and parts of the Catskill and Allegheny mountains.
Kestrels 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 rodents, frogs, reptiles, and even smaller birds (hence the name Sparrowhawk, as they were once known).
Despite their distribution and relative abundance throughout the eastern United States, kestrel numbers have significantly and steadily declined in the past fifty years, particularly in the Northeast. Regions surrounding the Adirondack, Allegheny, 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 (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 essential habitats are disappearing and becoming fragmented due to development, intensive agriculture, and plant succession.
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. Also, 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 severe 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 former 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.
The Peregrine Fund's American Kestrel Partnership has been actively studying the breeding ecology and factors influencing the decline of the species. NYSDEC and private landowners participate in this partnership by installing and monitoring nest boxes.