North American Kestrel Habitats: Cavity Nests, Pale Eggs, Rufous Bodies

Summary: American kestrel habitats seasonally in Canada and Mexico, year-round in the Caribbean and the United States have rufous bodies, pale eggs, cavity nests.

American kestrel (Falco sparverius) in flight at Laguna Atascosa National Wildlife Refuge, Lower Rio Grande Valley, South Texas; 2009: Robert Burton/USFW (U.S. Fish and Wildlife Service), Public Domain, via USFWS Digital Library

North American kestrel habitats assist cultivators through Falconidae raptor family member appetites for foraging birds, insects and reptiles and hunters and naturalists through distribution ranges in Canada, Mexico and the United States.

American kestrels bear their common name and the scientific name Falco sparverius as a French loan word for bird of prey and Latin for sparrow-like falcon. Agro-industry, pesticides, pollution, powerlines, predation, recreation, tourism and urbanization challenge the American kestrel, classified in 1758 by Swedish zoologist Carl Linnaeus (May 23, 1707-Jan. 10, 1787). In winter, bigger, more aggressive females drive the smaller, subordinate male away from open, prey-rich deserts, farmlands and grasslands into prey-poor woodlands counterproductive to hover-and-search hunting.

Ten- to 15-year lifespans expect cliffs, cultivated lands, deserts, fallow farmlands, grasslands, open woodlands, orchards and urban areas with nest-worthy buildings, earth mounds, nest-boxes or trees.

March to June facilitate brooding one to two three- to seven-egg clutches by following two- to three-day egg-laying intervals and filling later-laid yolks with more testosterone.

Mothers-to-be gather little or no material for cavity nests in abandoned flicker or pileated woodpecker holes, building eaves, earth and rocky mounds, nest-boxes or tree holes. Nests house brown-blotched or gray-dotted, mottled or speckled, buff, cinnamon, cream or pink-white, 1.18- to 1.49-inch (30- to 38-millimeter) by 0.94- to 1.14-inch (24- to 29-millimeter) eggs. Mothers-to-be, with fathers-to-be foraging, initiate 28- to 35-day incubations from the first egg-laying for different-aged, different-sized hatchlings from eggs 10 percent larger than maternal size indicates.

Habitat loss by brush, hedgerow and tree removal, land clearances and pesticide use and predation by drivers, hunters and natural enemies jeopardize North American kestrel habitats.

Semi-helpless chicks know an initially scanty white down as hatchlings open-eyed one day or two after hatching and a second creamy to yellow-white down as nestlings.

Chicks live off food foraged by fathers and shared by mothers until they learn hunting with both parents and then independently within 20 days of hatching. They manage adult calls two weeks after hatching, physical independence by moving away from parent-tended nests 30 days after hatching and sexual maturity 11 months later. Adults need beetles, butterflies, cicadas, crickets, dragonflies, grasshoppers, moths, scorpions and spiders during warmer months and frogs, lizards, mice, shrews, snakes, songbirds and voles during cold.

North American kestrel habitats up to 4,300 feet (1,310.64 meters) above sea level offer winter's coldest temperatures at minus 45 degrees Fahrenheit (minus 42.77 degrees Celsius).

Keen eyesight and two black, eye-like spots on the backs of heads protect kestrels from bobcats, coyotes, great-horned owls, prairie falcons, raccoons, red-tailed hawks and skunks.

Barred, rufous upperparts, cinnamon-tan breasts, dark vertical head-stripes, gray tooth-and-notch bills, light undertail feathers, spotted underparts and yellow-orange feet and legs quicken brown-eyed, long-winged adult identifications. Adult females reveal barred, rufous tails and wings and adult males dark-barred or spotted blue-gray wings, outer flight feathers dark like females and part-barred light undertails. Delicate, hovering, moth-like flight on 20.1- to 24-inch (51.05- to 60.96-centimeter) wingspans suggests 3.5- to 5-pound (1.59- to 2.27-kilogram), 8.7- to 12.2-inch (22.09- to 30.99-centimeter) adults.

Distressed, excited, high-pitched killy-killy-killy calls, fast chitter during courtship and mating and long whines by feeding adults and hungry offspring tell of North American kestrel habitats.

illustration of eggs of American kestrel under synonymous common name of sparrow hawk and scientific synonym of Tinnunculus sparverius; Illustrations of the Nests and Eggs of Birds of Ohio, Plate XLIV, figure 1, opposite page 170: Public Domain, via Biodiversity Heritage Library

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

American kestrel (Falco sparverius) in flight at Laguna Atascosa National Wildlife Refuge, Lower Rio Grande Valley, South Texas; 2009: Robert Burton/USFW (U.S. Fish and Wildlife Service), Public Domain, via USFWS Digital Library @ https://digitalmedia.fws.gov/cdm/singleitem/collection/natdiglib/id/13901/rec/9

illustration of eggs of American kestrel under synonymous common name of sparrow hawk and scientific synonym of Tinnunculus sparverius; Illustrations of the Nests and Eggs of Birds of Ohio, Plate XLIV, figure 1, opposite page 170: Public Domain, via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/34908293

For further information:

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