American Kestrel
Facts
Also known as: Sparrow Hawk
Conservation Status: Least Concern
Location: North and South America
Lifespan: Average 15 months. Oldest wild 11 years and 7 months. Oldest captive 17 years.
Also known as: Sparrow Hawk
Conservation Status: Least Concern
Location: North and South America
Lifespan: Average 15 months. Oldest wild 11 years and 7 months. Oldest captive 17 years.
Purple: year round
Orange: summer (breeding)
Blue: Winter (non breeding)
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Falconidae
Genus: Falco
Species: F. sparverius
Binomial name: Falco sparverius
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Falconidae
Genus: Falco
Species: F. sparverius
Binomial name: Falco sparverius
Description
Length: 7 to 8 in (19 to 21 cm)
Wingspan: 20 to 24 in (50 to 60cm)
Weight: Male - 103 to 120 g (3.6 to 4.2 oz). Female - 126 to 166 g (4.4 to 5.9 oz)
Other: At about the size of a large thrush, the American Kestrel is the smallest falcon in North America. The American Kestrel is sexually dimorphic, although there is some overlap in plumage coloration between the sexes. Plumage has more variation between the sexes than 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. While the kestrel is perched, the wingtips are noticeably shorter than the tail tip.
Length: 7 to 8 in (19 to 21 cm)
Wingspan: 20 to 24 in (50 to 60cm)
Weight: Male - 103 to 120 g (3.6 to 4.2 oz). Female - 126 to 166 g (4.4 to 5.9 oz)
Other: At about the size of a large thrush, the American Kestrel is the smallest falcon in North America. The American Kestrel is sexually dimorphic, although there is some overlap in plumage coloration between the sexes. Plumage has more variation between the sexes than 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. While the kestrel is perched, the wingtips are noticeably shorter than the tail tip.
Subspecies
- F. s. sparverius, described by Linnaeus in 1758, is the nominate subspecies. It is found in most of the United States, Canada, and Mexico.
- F. s. paulus, described by Howe and King in 1902, is found in the Southeast United States, from Louisiana to Florida.
- F. s. peninsularis, described by Mearns in 1892, is found in southern Baja California.
- F. s. tropicalis, described by Griscom in 1930, is found from southern Mexico to northern Honduras.
- F. s. nicaraguensis, described by Howell in 1965, is found in Honduras and Nicaragua.
- F. s. sparveroides, described by Vigors in 1827, is found in Cuba and the Isle of Youth, and southern to central Bahamas.
- F. s. dominicensis, described by Gmelin in 1788, is found in Puerto Rico through the Lesser Antilles to Grenada.
- F. s. caribaearum, described by Gmelin in 1788, is found in Hispaniola.
- F. s. brevipennis, described by Berlepsch in 1892, is found in the Netherlands Antilles.
- F. s. isabellinus, described by Swainson in 1837, is found from Venezuela to northern Brazil.
- F. s. ochraceus, described by Cory in 1915, is found in eastern Colombia and northwest Venezuela.
- F. s. caucae, described by Chapman in 1915, is found in western Colombia.
- F. s. aequatorialis, described by Mearns in 1892, is found in northern Ecuador.
- F. s. peruvianus, described by Cory in 1915, is found in southwest Ecuador, Peru, and northern Chile.
- F. s. fernandensis, described by Chapman in 1915, is found on the Juan Fernández Islands off Chile.
- F. s. cinnamominu, described by Swainson in 1837, is found in Peru, Chile, and Argentina.
- F. s. cearae, described by Cory in 1915, is found from northeast Brazil south to eastern Bolivia.
Behaviour
The American Kestrel has 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, but the larger females typically have lower-pitched voices than the males. The "whine" call is primarily associated with feeding, but is also uttered during copulation. The "chitter" is used in activities which involve interaction between male and female birds, including courtship feeding, copulation, and the feeding of nestlings. Nestlings can produce calls similar to those of adults at 16 days old. 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 degrees 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 has 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, but the larger females typically have lower-pitched voices than the males. The "whine" call is primarily associated with feeding, but is also uttered during copulation. The "chitter" is used in activities which involve interaction between male and female birds, including courtship feeding, copulation, and the feeding of nestlings. Nestlings can produce calls similar to those of adults at 16 days old. 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 degrees 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.
Predators or Prey?
The American kestrel is often preyed on by other raptors including the red-tailed hawk, northern goshawk, Cooper's hawk, peregrine falcon, barn owl, and great horned owl. Prey is almost always caught on the ground. Before striking, the kestrel characteristically bobs its head and tail, then makes a direct flight toward the prey to grab it in its talons. During the breeding season, the bird will carry large prey back to its mate or young. One study found that an American Kestrel pair "foraged in ways that minimized the costs of energy acquisition in its particular situation". For example, if the success rate for catching prey decreases significantly in a particular area, the bird will move to a different area.
The American kestrel is often preyed on by other raptors including the red-tailed hawk, northern goshawk, Cooper's hawk, peregrine falcon, barn owl, and great horned owl. Prey is almost always caught on the ground. Before striking, the kestrel characteristically bobs its head and tail, then makes a direct flight toward the prey to grab it in its talons. During the breeding season, the bird will carry large prey back to its mate or young. One study found that an American Kestrel pair "foraged in ways that minimized the costs of energy acquisition in its particular situation". For example, if the success rate for catching prey decreases significantly in a particular area, the bird will move to a different area.
Diet
American Kestrels feed largely on small animals such as grasshoppers, dragonflies, lizards, mice, and voles. They will also eat other small birds. The kestrel has also been reported to have killed larger animals such as snakes, bats, and squirrels. The kestrel maintains high population densities, 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 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 in the air.
American Kestrels feed largely on small animals such as grasshoppers, dragonflies, lizards, mice, and voles. They will also eat other small birds. The kestrel has also been reported to have killed larger animals such as snakes, bats, and squirrels. The kestrel maintains high population densities, 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 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 in the air.
Habitat
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 meters (14,764 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 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 meters (14,764 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.
Conservation
Kestrels are not considered to be globally threatened and are the commonest bird of prey in Europe, although kestrels have declined in Britain in the last few years.
Kestrels are not considered to be globally threatened and are the commonest bird of prey in Europe, although kestrels have declined in Britain in the last few years.
Reproduction
Kestrels nest on a ledge, in a tree hole or in a disused nest. Breeding begins April to may. The clutch of 3 - 6 eggs is incubated by the female and the chicks hatch after 27 - 31 days. The eggs measure around 39 millimetres by 32 millimetres. They are smooth and non-glossy and coloured white or yellowish-buff with red-brown markings. Both adults feed the young birds, though the newly-hatched are usually fed by the female with the male hunting and bringing the food to the nest. Juveniles fledge after 27 - 39 days and disperse from their natal grounds in July - August and may travel up to 100 miles (150 kilometres).
Kestrels nest on a ledge, in a tree hole or in a disused nest. Breeding begins April to may. The clutch of 3 - 6 eggs is incubated by the female and the chicks hatch after 27 - 31 days. The eggs measure around 39 millimetres by 32 millimetres. They are smooth and non-glossy and coloured white or yellowish-buff with red-brown markings. Both adults feed the young birds, though the newly-hatched are usually fed by the female with the male hunting and bringing the food to the nest. Juveniles fledge after 27 - 39 days and disperse from their natal grounds in July - August and may travel up to 100 miles (150 kilometres).
