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Falco mexicanusprairie falcon

By Matthew Goulet

Geographic Range

Falco mexicanus is found throughout the western United States as well as parts of Mexico and Canada. It is commonly found in the desert and prairie regions of British Columbia, Alberta, and Saskatchewan in Canada. In the United States, Falco mexicanus is found from North and South Dakota south to Texas, Arizona, and New Mexico. Sightings in Manitoba, Minnesota, Illinois, Iowa, and Indiana have been recorded as well. (Steenhof, 1998; Terres, 1980)

Habitat

In spring and fall migrations, prairie falcons prefer open grassland habitats, although they are found in forested habitats in Canada during migrations as well. In winter, prairie falcons prefer open desert and grassland habitats. Prairie falcons breed in open, arid grasslands with cliffs and bluffs for nesting. Nesting sites are commonly shared with common ravens (Corvus corax), golden eagles (Aquila chrysaetos), and red-tailed hawks (Buteo jamaicensis). (Steenhof, 1998)

  • Range elevation
    3350 (high) m
    10990.81 (high) ft

Physical Description

Prairie falcons are large, pale brown falcons with squarish heads and large, dark eyes. Characteristic facial features include black malar streaks, a dark ear patch, and a distinctive white patch between the eyes and ear patch. About one year after birth, at full maturation, the bill horn is dark-bluish and yellow at the base. Yellow feet and a white throat also distinguish adults. When perched, the wings are shorter than the tail tip. Prairie falcons can be identified while in flight by their dark axillaries and a “trailing edge of underwing-coverts”. These stand out against the light colored underwing surface of the bird. Prairie falcons are distinguishable from similar looking falcons by dark, triangular patches on the undersurface of their pale wings. Females tend to be larger in size and have greater basal metabolic rates than males. Prairie falcons can be difficult to spot in their natural habitat, as plumage color blends in naturally with colors of the cliffs on which they nest. Prairie falcons are sometimes confused with Swainson's hawks (Buteo swainsoni), merlins (Falco columbarius), and peregrine falcons (Falco peregrinus). (Sibley, 2003; Steenhof, 1998; Terres, 1980)

  • Sexual Dimorphism
  • female larger
  • Range mass
    420 to 1100 g
    14.80 to 38.77 oz
  • Range length
    37 to 47 cm
    14.57 to 18.50 in
  • Average length
    41 cm
    16.14 in
  • Range wingspan
    90 to 113 cm
    35.43 to 44.49 in
  • Average wingspan
    102 cm
    40.16 in
  • Average basal metabolic rate
    390.2 (males) 504.8 (females) cm3.O2/g/hr

Reproduction

Prairie falcons are monogamous during the breeding season. Pairs are established upon arriving at the breeding grounds. The mating system is similar to that of peregrine falcons (Falco peregrinus) and gryfalcons (Falco rusticolus). Courtship behaviors include ledge displays, head-low bows, mutual soaring, and different vocalizations. Males use food and vocalizations to attract females to ledges. Copulation between prairie falcons lasts about 10 seconds. Copulation begins more than 51 days before the clutch is completed. Males during courtship tend to females by bringing food to the nesting site. (Steenhof, 1998)

Prairie falcons don't construct nests, rather they create a scrape on a ledge. They breed from February to July, with a peak from April to May. They lay from 2 to 6 eggs at 2 day intervals. Incubation lasts about 29 to 31 days. Young are fledged at 29 to 47 days old and become independent a little more than 2 months after hatching. Prairie falcons become sexually mature within 2 years after hatching. (Steenhof, 1998; Steenhof, 1998)

  • Breeding interval
    Prairie falcons breed once yearly.
  • Breeding season
    Late February through July, with peak activity between April and May.
  • Range eggs per season
    2 to 6
  • Average eggs per season
    5
  • Average eggs per season
    4
    AnAge
  • Range time to hatching
    29 to 31 days
  • Range fledging age
    29 to 47 days
  • Average time to independence
    65 days
  • Range age at sexual or reproductive maturity (female)
    1 to 2 years
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

Females perform the majority of incubation and brooding. Males begin sharing incubation duties during the egg laying process but the amount of time a male incubates varies greatly. Young hatch with open ear holes and slightly open eyes. Parental attendance at the nest decreases 1 to 2 days after hatching, within 28 days of hatching the parents no longer brood the young. During the first three weeks after hatching, both parents feed the young. Usually, the male brings food to the female who passes it to the young. After 4 weeks, parents drop food at the ledge of the nest and chicks begin to feed themselves. (Steenhof, 1998)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
    • protecting
      • female

Lifespan/Longevity

One calculation predicted Falco mexicanus longevity to be 15.6 years. More common, however, is a 2.4 to 4.9 year life span in the wild. Shooting by humans is the number one cause of death for prairie falcons. Collisions with manmade objects, such as vehicles, wires, and fences, is the second leading cause of death in adult falcons. Some adults have been known to drown in stock tanks as well. Predation by great horned owls (Bubo virginianus) leads to deaths as well. In eggs and nestlings, ectoparasites, predation, human disturbance, and starvation are leading causes of mortality. The average post-fledgling mortality rate is 31%. (Steenhof, 1998)

  • Range lifespan
    Status: wild
    9.1 (high) years
  • Range lifespan
    Status: captivity
    10 (high) hours
  • Typical lifespan
    Status: wild
    2.4 to 4.9 years

Behavior

Prairie falcons are mainly solitary and are only found in pairs during the breeding season. Play-like behavior has been observed in prairie falcons, as well. Birds were observed tossing dried cow manure from their talons and attempting to catch it again in mid-air. (Steenhof, 1998)

Prairie falcon flight is distinguished by shallow, stiff wing beats. They are able to soar 4 to 5 times longer distances by flattening their wings and fanning its tail. Adult prairie falcons spend 4 to 6 percent of their day preening. Dust bathing is the most common form of self-maintenance, but they do bathe in standing water where available. Prairie falcons stop flying about a half hour before sunset, however, nocturnal flight has been recorded. Most flight takes place throughout the middle of the day. (Steenhof, 1998)

Prairie falcons are widely considered the most aggressive of all raptors. Nesting adults will attack other prairie falcons that enter their territory as well as other sympatric raptor species, including golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), California condors (Gymnogyps californianus), great horned owls (Bubo virginianus), and terrestrial predators. No aggresive responses have been noted towards American kestrels (Falco sparverius), northern harriers (Circus cyaneus), sharp-shinned hawks (Accipiter striatus), and turkey vultures (Cathartes aura). (Steenhof, 1998)

  • Range territory size
    59 to 315 km^2

Home Range

The size of the home range varies geographically. Males tend to have larger home ranges than females. Home range size tends to decrease in the winter and increase throughout the breeding season. (Steenhof, 1998)

Communication and Perception

Vocalization is the most common form of communication in prairie falcons, but vocalizations have not been well studied. Three types of calls have been documented: cacking calls are territorial and alarm vocalizations, eechup calls are used during courtship and ledge displays, and chitter calls are used in aggressive situations. The cacking call is a loud, shrill kik-kik-kik. (Steenhof, 1998)

Food Habits

During the breeding season the most common prey for these falcons are ground squirrels (Spermophilus), including Townsend’s ground squirrels (Spermophilus townsendii), Belding’s ground squirrels (Spermophilus beldingi) and Richardson’s ground squirrels (Spermophilus richarsonii). These falcons also eat small birds, such as horned larks (Eremophila alestris), western meadowlarks (Sturnella neglecta), mourning doves (Zenaida macroura), brown-capped rosy finches (Leucosticte ausralis), and blackbirds (Icteridae). Reptiles and large insects may also be taken. (Steenhof, 1998; Terres, 1980)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • birds
  • mammals
  • reptiles
  • insects

Predation

Nestlings and eggs are most susceptible to predation. Mammalian predators, especially coyotes and bobcats, prey on nestlings and eggs. Great horned owls prey on both adults and nestlings. Remains of prairie falcons have been found in golden eagle pellets as well. Prairie falcons are aggressive in defense of their territories and nests. They are agile in flight and may avoid predation through agility and aggression. Prairie falcons have been observed defending themselves against great horned owls, resulting in the death of the owl in some cases. (Steenhof, 1998)

Ecosystem Roles

Prairie falcons help keep ground squirrel populations in check as their main source of prey. They are also predators of other bird species. Prairie falcons are top predators, but are sometimes preyed on by larger birds of prey, such as golden eagles and great horned owls. Prairie falcon eggs and fledglings are sometimes taken by coyotes and bobcats. (Steenhof, 1998)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Prairie falcons have been and continue to be important birds for education and scientific research. Their abundance allow for easy studying. They are also the second most frequently harvested bird in the United States for falconry, with nineteen states allowing regulated captures of prairie falcons. Prairie falcons also help to regulate populations of ground squirrels and other rodents. (Steenhof, 1998)

  • Positive Impacts
  • ecotourism
  • research and education
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Falco mexicanus on humans.

Conservation Status

Falco mexicanus has a wide range and large global population and is considered a low conservation risk currently. Prairie falcon populations do not seem to be declining. (Ekstrom and Butchart, 2006)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Matthew Goulet (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

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

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

carnivore

an animal that mainly eats meat

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.

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

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).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

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.

seasonal breeding

breeding is confined to a particular season

sexual

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

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

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

Ekstrom, J., S. Butchart. 2006. "IUCN Red List of Threatened Species" (On-line). Falco mexicanus. Accessed November 14, 2006 at http://www.iucnredlist.org/search/details.php/49517/summ.

Sibley, D. 2003. The Sibley Field Guide to Birds of Western North America. New York: Alfred A. Knopf, Inc..

Steenhof, K. 1998. Prairie Falcon (Falco Mexicanus). Pp. 1-28 in A Poole, F Gill, eds. The Birds of North America, No. 346, Vol. 9, 1 Edition. Philadelphia, PA: The Birds of North America, Inc..

Terres, J. 1980. Falcon, prairie. Pp. 273-274 in J Terres, ed. The Audubon Society Encyclopedia of North American Birds, Vol. 1, 1 Edition. New York: Alfred A. Knopf, Inc..

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