American Kestrel

## Description

The American kestrel (Falco sparverius ), also called the sparrow hawk, is the smallest and most common falcon in North America. It has a roughly two-to-one range in size over subspecies and sex, varying in size from about the weight of a blue jay to a mourning dove. It also ranges to South America and is a well-established species that has evolved into 17 subspecies adapted to different environments and habitats throughout the Americas. It exhibits sexual dimorphism in size (females being moderately larger) and plumage, although both sexes have a rufous back with noticeable barring. Its plumage is colorful and attractive, and juveniles are similar in plumage to adults.

The American kestrel usually hunts in energy-conserving fashion by perching and scanning the ground for prey to ambush, though it also hunts from the air. It sometimes hovers in the air with rapid wing beats while homing in on prey. Its diet typically consists of grasshoppers and other insects, lizards, mice, and small birds (e.g. sparrows). This broad diet has contributed to its wide success as a species. It nests in cavities in trees, cliffs, buildings, and other structures. The female lays three to seven eggs, which both sexes help to incubate.

Its breeding range extends from central and western Alaska across northern Canada to Nova Scotia, and south throughout North America, into central Mexico and the Caribbean. It is a local breeder in Central America and is widely distributed throughout South America. Most birds breeding in Canada and the northern United States migrate south in the winter. It is an occasional vagrant to Western Europe.

Based on appearance and behavior it was for many years considered a member of the primarily European and African kestrel clade within the genus Falco, but DNA analysis shows the American kestrel to actually be genetically more closely related to the larger American falcons such as the aplomado, peregrine, and prairie falcons. Though the species has not been renamed as a result of these genetic analyses, it is not actually a kestrel in the phylogenetic sense. Instead, a process of convergent evolution to fit a similar small prey niche in the ecosystem as the true kestrels have left it with similar physical characteristics and hunting methods.

The American kestrel is a common bird used in falconry, especially by beginners. Though not as strong a flyer as many other, larger falcons, proper training and weight control by the falconer allows many American kestrels to become effective hunters of birds in the size range of sparrows and starlings, with occasional success against birds up to approximately twice their own weight.

## Appearance

The American kestrel is the smallest and most common falcon in North America. In contrast to many other raptors, the males and the females in this species differ more in plumage than in size. Males have blue-grey wings with black spots and white undersides with black barring. Their 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. Their tail is rufous in color with numerous narrow dark black bars.

## Distribution

The breeding range of American kestrels extends from central and western Alaska across northern Canada to Nova Scotia, and south throughout North America, into central Mexico and the Caribbean. They are local breeders in Central America and are widely distributed throughout South America. Most birds breeding in Canada and the northern United States migrate south in the winter, sometimes going as far as Central America and the Caribbean. 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. Their habitat must include perches, open space for hunting, and cavities for nesting.

## Behavior

Outside of the breeding season, American kestrels spend their time singly. They usually hunt by day in energy-conserving fashion; they perch and scan the ground for prey to ambush or may also hunt from the air. They are often seen along roadsides or fields perched on objects such as trees, overhead power lines, or fence posts. They also hunt by kiting, hovering in the air with rapid wing beats and scanning the ground for prey. Other hunting techniques include a low flight over fields or chasing insects and birds in the air. Prey is most often caught on the ground, though occasionally they take birds in flight. Before striking, the kestrel characteristically bobs its head and tail, then makes a direct flight toward the prey to grab it in its talons. American kestrels communicate with thelp of three basic vocalizations - the "klee" or "killy", the "whine", and the "chitter". The "klee" is usually delivered as a rapid series - klee, klee, klee, klee when the kestrel is upset or excited. This call is used in a wide variety of situations and is heard from both sexes. The "whine" call is primarily associated with feeding. The "chitter" is used in courtship feeding, mating, and feeding of nestlings.

## Diet

American kestrels are carnivores and feed largely on small animals such as grasshoppers, dragonflies, lizards, mice, voles, and small birds. They may also hunt snakes, bats, and squirrels.

## Reproduction

American kestrels are monogamous and form strong long-lasting pair bonds. In migratory populations, the males arrive at the breeding ground before females, then the female selects a mate. Males perform elaborate dive displays to advertise their territory and attract a mate. These displays consist of several climbs and dives, with three or four "klee" calls at their peaks. Pairs usually use previous nesting sites in consecutive years. American kestrels are cavity nesters, but they are able to adapt to a wide variety of nesting situations. They generally prefer natural cavities (such as in trees) but will also nest in holes created by large woodpeckers, or use the abandoned nests of other birds. They may even nest on cliff ledges and building tops, or utilize nesting boxes. The female lays 3 to 7 eggs which are white to cream in color with brown or grey splotching. Incubation usually lasts 30 days and is mainly done by the female. Hatchlings are altricial (helpless) and are only able to sit up after 5 days. They grow very quickly, reaching an adult weight after 16-17 days. After 28-31 days, they are able to leave the nest and depend on their parents another 2 or 3 weeks. American kestrels usually reach reproductive maturity and may breed from a year old.

## Population

### Population threats

The main threat to American kestrels is habitat loss as a result of longleaf pines being cleared from agricultural fields. They also suffer from competition with other birds for nest sites, from hunting and trapping, road collisions and predation by other raptors.

### Population number

According to the All About Birds resource the total population size of the American kestrel is around 9.2 million individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.

## Fun Facts for Kids

American kestrels have two black spots (ocelli) on each side of their 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 kestrels from potential attackers.

The American kestrel is also known as grasshopper hawk, due to its diet, and killy hawk, due to its distinct call.

There are 17 subspecies of the American kestrel and each varies in color, size, and vocalizations.

The American kestrel is commonly used in falconry, especially by beginners. Though not as strong a flyer as many other, larger falcons, proper training and weight control by the falconer allows many American kestrels to become effective hunters of birds such as sparrows and starlings.