In contrast to many other raptor species, the sexes differ more in plumage than in size. Males have blue-grey wings with black spots and white undersides with black barring. The back is rufous, with barring on the lower half. The belly and flanks are white with black spotting. The tail is also rufous, with a white or rufous tip and a black subterminal band. The back and wings of the female American kestrel are rufous with dark brown barring. The undersides of the females are creamy to buff with heavy brown streaking. The tail is noticeably different from the male’s, being rufous in color with numerous narrow dark black bars. Juveniles exhibit coloration patterns similar to the adults’. In both sexes, the head is white with a bluish-grey top. There are also two narrow, vertical black facial markings on each side of the head, while other falcons have one. Two black spots (ocelli) can be found on each side of the white or orangish nape.The function of these spots is debated, but the most commonly accepted theory is that they act as “false eyes”, and help to protect the bird from potential attackers. The wings are moderately long, fairly narrow, and taper to a point.
American kestrels in Canada and the northern United States typically migrate south in the winter, sometimes going as far as Central America and the Caribbean. Birds that breed south of about 35° north latitude are usually year-round residents. Migration also depends on local weather conditions. Wintering kestrels’ choice of habitat varies by sex. Females are found in open areas more often than males during the non-breeding season. A common explanation for this behavior is that the larger females arrive at the preferred habitat first and exclude males from their territory.
The American kestrel is not long-lived, with a lifespan of <5 years for wild birds. The oldest banded wild bird was 11 years and 7 months, while captive kestrels can live up to 14–17 years. In a study, humans accounted for 43.2% of 1,355 reported deaths, which included direct killing and roadkills, while predation (including by larger birds of prey) accounted for 2.8%. This statistic is likely biased, however, as reported deaths are usually found near or in areas populated by humans.
In the wild
American kestrels are found in a wide variety of habitats, including grasslands, meadows, deserts, and other open to semiopen regions. They can also be found in both urban and suburban areas. A kestrel’s habitat must include perches, open space for hunting, and cavities for nesting (whether natural or man-made). The American kestrel is able to live in very diverse conditions, ranging from above the Arctic Circle, to the tropics of Central America, to elevations of over 4,500 m (14,800 ft) in the Andes Mountains. The bird is distributed from northern Canada and Alaska to the southernmost tip of South America, Tierra del Fuego. It is the only kestrel found in the Americas. It has occurred as a vagrant in the UK, Denmark, Malta and the Azores.
American kestrels feed largely on small animals such as grasshoppers, dragonflies, lizards,mice, and voles. They will occasionally eat small birds. The kestrel has also been reported to have killed snakes, bats and squirrels. The kestrel is able to maintain high population densities, at least in part because of the broad scope of its diet. The American kestrel’s primary mode of hunting is by perching and waiting for prey to come near. The bird is characteristically seen along roadsides or fields perched on objects such as trees, overhead power lines, or fence posts. It also hunts by kiting, hovering in the air with rapid wing beats and scanning the ground for prey. Other hunting techniques include low flight over fields, or chasing insects and birds in the air.