The American Kestrel (Falco sparverius) is the smallest and most common falcon in North America.
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 consists of grasshoppers and other insects, lizards, mice, and small birds.
It nests in cavities in trees, cliffs, buildings, and other structures. The female lays three to seven eggs, which both sexes help to incubate.
Information & Facts:
The American Kestrel ranges from 22 to 31 cm (8.7 to 12.2 in) in length with a wingspan of 51–61 cm (20–24 in). The female kestrel is larger than the male, though less so than larger falcons, being around 10% to 15% larger within a subspecies.
Physically, American Kestrels are leaner and less muscular than larger falcons. The pectoral flight muscles of the American kestrel make up only about 12% of its body weight, as compared to about 20% for the strongest flying falcons such as the peregrine. The wings are moderately long, fairly narrow, and taper to a point.
Their less muscular body type is adapted to energy conserving ambush hunting, rather than spending large amounts of energy consuming time on the wing and getting into long tail-chases of bird prey. For their size, they have strong talons and beaks, and can swiftly dispatch prey. Their lean build and energy conserving strategy allows a lower daily food intake than if they were more strongly muscled, yet with enough strength to commonly take bird prey as large as themselves, and occasionally larger.
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. 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 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 range of the American Bittern includes much of North America. It breeds in southern Canada as far north as British Columbia, the Great Slave Lake and Hudson Bay, and in much of the United States and possibly central Mexico.
It migrates southward in the fall and to the southern United States of the Gulf Coast region, very commonly in the marshy Everglades of Florida, the Caribbean Islands and Mexico. They are also seen in Panama and Costa Rica. It is an aquatic bird and frequents bogs, marshes and the thickly-vegetated verges of shallow-water lakes and ponds, both with fresh and brackish or saline water.
It sometimes feeds out in the open in wet meadows and pastures.
The American Kestrel feeds largely on small animals such as grasshoppers, dragonflies, lizards, mice, voles, and small birds. The kestrel has also been reported to have killed snakes, bats, and squirrels.
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.
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. Much like the red-tailed hawk, American kestrels conserve energy in a hunt and pick their attacks with care as to position and odds of success.
During the breeding season, the bird will carry large prey back to its mate or young.
American Kestrels are sexually mature by their first spring. In migratory populations, the males arrive at the breeding ground before females, then the female selects a mate. Pair bonds are strong, often permanent. Pairs usually use previous nesting sites in consecutive years.
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. Females are promiscuous for about one to two weeks after their arrival at the nesting site. This is thought to stimulate ovulation. Food transfers from the male to the female occur from about four to five weeks prior to egg laying to one to two weeks after..