Falco mexicanus
prairie falcon

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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

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)