The smallest falcon in New York City—in fact, the smallest in North America—is the American Kestrel (Falco sparverius). At 9-12 inches long with a 21-inch wingspan and weighing about 4 ounces, it is about the size of a Blue Jay or Mourning Dove.
Although this falcon is declining in the Northeastern U. S., it is the most common raptor in New York City. One survey found 75 nesting sites around the city. It can be found in all five boroughs, although they are easy to miss, because they are small and very fast. The larger peregrines and red-tailed hawks are much easier to spot. Some Brooklyn locations where kestrels have been seen are Floyd Bennett Field, Green-Wood Cemetery, Jamaica Bay, and Brooklyn Bridge Park.
Kestrels are attractive birds with distinctive markings. The colorful males have blue-gray wings and reddish-brown backs with dark horizontal bars. The slightly larger females' wings are the same color as their backs. Other identification marks include a bold, helmet-like head pattern, with a blue cap (brighter in males), and a spot of white on the throat. In the city, kestrels can often be seen perched on old TV antennas, water towers, light poles, and other high structures. They often will return to the same favorite perches again and again, so if you see one, look in the same place for it at other times. They may pump or bob their tails up and down while perched, a characteristic behavior that distinguishes the kestrel from other falcons and helps to identify them at a distance when markings are not visible.
American kestrels often nest in old buildings in New York City, usually in holes in the cornices of brownstones or row houses. In Staten Island and Queens they also nests in boxes placed near landfills. Outside the city, they nest in hollow trees or old barns and prefer open or semi-open habitats such as grasslands. American Kestrels are highly adaptable and can live almost anywhere that offers some open ground for hunting and perches that have a good view of the surroundings, such as telephone wires.
Kestrels can breed at one year of age. They often form monogamous pairs that stay together from year to year. The breeding season lasts from mid spring through summer. They lay from three to seven eggs and may raise two broods in a season. The eggs are incubated for about a month, and the nestlings fledge about a month after hatching, but may continue to be fed by the parents for another week or two and may stay with them through late summer. American kestrels have been reported to live up to 11 years, but most live far shorter lives.
Kestrels feed on insects, especially dragonflies, and other small prey such as lizards, mice, and house sparrows. In the summer, they usually hunt large insects in the early morning and evening; in the winter, they hunt small birds and rodents throughout the daytime.
Kestrels make a call that sounds like "klee" or "killee." In their hovering-hunting flight maneuver, they face the wind, flare their tails, and beat their wings to hang still while they scan the ground for prey. Kestrels may be preyed on by, and will sometimes harry, larger raptors and owls. Other predators include coyotes, bobcats, skunks, raccoons, crows, and ravens. The relative lack of these animals in the city may explain why kestrels seem to thrive here.
Kestrels range throughout North and South America. Some birds, especially from the far north, migrate, but southern and urban birds may stay put year-round. It is not known whether New York City's kestrels migrate or are resident all year.