More Information

Additional Information

Falco sparveriusAmerican kestrel

By Kathryn McCollough

Geographic Range

The American kestrel permanently inhabits (without seasonal migration) North and South America from near the tree-line in Alaska and Canada and south to Tierra del Fuego. The bird can also be found in the West Indies, the Juan Fernandez Islands and Chile. It is largely absent from heavily forested areas, including Amazonia.

Habitat

The American kestrel nests in tree cavities, woodpecker holes, crevices of buildings, holes in banks, nest boxes or, rarely, old nests of other birds. The American kestrel is highly adaptable behaviorly and lives just about everywhere, as long as there is some open ground for hunting and conspicuous places on which to perch (e.g., telephone wires).

Physical Description

male: 103g to 120g

female: 126g to 166g

Generally, the American kestrel is 19 - 21 cm in length with an average wingspan of 50 - 60 cm.

Excepting the Seychelles kestrel, the American kestral is the smallest species in the genus Falco. There is a strong selection for sexual dichromatism, with males being brightly and rufously colored and females having a more even tone.

  • Average mass
    117 g
    4.12 oz
    AnAge

Reproduction

For up to six weeks before egg laying, females are promiscuous, mating with two or three males. Once a female settles with one mate, the pair mate frequently until egg laying. Three to seven eggs are laid (usually 4 or 5) over a period of 2 or 3 days. Eggs are white, cream or pale pink with an average size of 35 x 29 mm. Laying dates vary with geographical location:

Chile: September - October

Trinidad: May

Curacao: January

Florida: mid-March - early June

Central USA: mid-April - early June

Canada: late May - mid-June

The female does most of the incubation, but males have been known to occasionally sit. Both sexes have brooding patches. Incubation lasts 29 - 30 days and hatched chicks are non-competitive. Once chicks have hatched, females beg food from males. The female, in turn, feeds the young for the first 20 days. After that period, chicks beg for food from males and feed themselves. After 30 days, chicks leave the nest. The family remains as a unit for some time. The survival rate of chicks is about 50% under natural conditions, but it is usually higher under better conditions (e.g., human-provided nesting boxes).

  • Average eggs per season
    5
    AnAge
  • Average time to hatching
    29 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    365 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    365 days
    AnAge

Lifespan / Longevity

Behavior

The American kestrel is, for the most part, not a social bird. During the mating season, males and females pair up and have joint territories. Presumably, the pair or the male defends the territory. The function of the territory may not be so much to ensure mating as to maintain a pair bond during the nesting season when the male is needed to help rear offspring.

Communication and Perception

Food Habits

In the summer, American kestrels hunt in the early morning and evening, eating large insects (mainly grasshoppers). During winter, they hunt throughout daylight hours and eat small mammals (mice and sparrow-sized birds), sandpiper chicks, lizards, scorpions and amphibians.

Economic Importance for Humans

Economic Importance for Humans: Positive

The American kestrel plays a prominent part in controlling creatures that humans usually consider a nuisance (mice, insects, etc.).

Conservation Status

The availability of nesting places (tree-cavities) may be the chief density limiting factor in breeding populations of American kestrels. This density can be increased by the installation of nesting boxes. However, whether or not additional nesting boxes are introduced, the bird is common.

Other Comments

The common name "sparrow-hawk" is a misnomer because the diet of Falco sparvarius is not even close to being exclusively made up of sparrows. Its other common name, "American kestrel," is more appropriate.

Contributors

Kathryn McCollough (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

Amadon, Dean and Leslie Brown, EAGLES, HAWKS AND FALCONS OF THE WORLD, McGraw-Hill Book Company, 1968, v 1 & 2, pp. 85, 771-776.

Cade, Tom J., THE FALCONS OF THE WORLD, Cornell University Press, Ithaca NY, 1982, pp. 152-160.

Sprunt, Alexander, jr. D. Sc., NORTH AMERICAN BIRDS OF PREY, Bonanza Books, NY MCMLV, pp. 158-161.

Search

Navigation Links

Information
Pictures
Sounds
Classification

Classification