The American kestrel, sometimes called “sparrow hawk”, is not a hawk at all. Certainly the bird’s pint-sized frame is small, thus “sparrow”, but the “hawk” in the common name is actually a misnomer. The bird of prey with pointed wings and beautiful plumage is actually a very small falcon.
In fact American kestrels are the smallest falcon in North America, not to mention being smaller than any hawk. Here’s an unbashful raptor that resides in a wide variety of habitats, will readily accept the accommodations of artificial nest-boxes, and is common throughout most of Minnesota. Kestrels are perhaps the most easily recognized and frequently observed raptor.
No other bird of prey in North America is so richly colored. Male kestrels sport a rusty back and tail, slate blue adorns his crown and wings, and a white terminal band tips his tail. White cheek patches are accented by two black "whisker" markings on each side of his head. Total length is about ten inches long and averaging slightly less than four ounces in weight. Not much for size, but any shortcoming are compensated by force and fearlessness.
Their diet is surprisingly general for such small falcons. Unlike other falcons, which capture most of their prey in the air (birds), kestrels capture much of their prey on the ground, though not always. Species of mammals make up about 70% of their diet, including rodents such as young ground squirrels, gophers, shrews, voles, mice, and rats. Even young cottontail rabbits are preyed upon.
Birds, about ten percent of their total diet, are hunted, too. Around twenty percent include insects such as grasshoppers, crickets, beetles, butterflies, moths, dragonflies, and worms, make up a significant part of a kestrel’s diet, and just one percent of their diet consists of reptiles and amphibians like snakes, salamanders, frogs, and toads.
A familiar kestrel habit will often give human admirers a good clue toward positive identification. Kestrels typically hunt by hovering in a near motionless—save for their fluttering wings—above grassy fields, ditches, or other likely small-rodent haunts. The raptor’s longish tail will be fanned, the body angled slightly upward, and the head tilted downward with eyes intensely riveted and searching for the movements of prey beneath tall vegetation.
Aided by headwinds, this mode of flight will be maintained indefinitely, occasionally dipping abruptly a few feet lower in altitude, only to regain the sedentary airborne posture if prey had yet to be sighted or secured. A complete free-fall to the ground below will occur if a hapless vole, mouse, or grasshopper fails to miss the clutches of the falcon's quick strike.
I’ve been lucky enough to enjoy the close company of a pair of kestrels nesting in one of my wood duck nest boxes. The pair took over a box that overlooked Assawa Lake that no doubt was chosen for the plentitude of small rodents and birds for prey, but maybe the view, too.
One season the pair took over a different box closer to my house. The box was designed as a sort of “catch all” box—one that would be suitable for a wide range of birds, including kestrels. The entrance hole was larger than a standard songbird hole, but smaller than the standard wood duck sized hole.
During a very hot couple of weeks in July 2011, the pair’s five chicks were almost full grown, but terribly crowded in the small box. Prey must have been hard to come by, and two of the larger chicks ended up killing and consuming three of their smaller and weaker nest mates. Though seemingly cruel, it is the way of Nature and often how it works with birds of prey. Not long after this incident, the two surviving chicks fledged and joined their parents to learn how to fly and hunt.
As it is, kestrel couples form their annual bonds through courtship rituals comprised of flights and calls. Soon after the male establishes or reestablishes a territory, he will perform numerous flights to fair heights above the trees and dive while emitting loud “klee, klee, klee” notes, typically at the apex of his display. He may also carry food to his mate and feed her.
The ceremony is designed to strengthen the ties that bind. And soon after copulation, egg laying and incubation commences. Somewhat unique for birds of prey where most of the incubation duties are carried out by females, male kestrels pitch in and share in this lengthy task. Generally anywhere from three to seven eggs are laid that hatch in about a month’s time.
When the chicks at last hatch, both parents begin hunting non-stop in order to satisfy the appetites of their growing offspring. After fledging, the kestrel family will remain intact for about a month until their fully grown youngsters begin their lives as independent adults as we get out and enjoy the great outdoors.
Blane likes to hear from his readers. Email him your favorite outdoors experiences and wildlife encounters at firstname.lastname@example.org.