The Prairie Falcon is a medium-sized falcon of the open, arid country of the west. It's lighter, brown-buff colors match well with tones of the landscapes over which it nests and hunts. This is a fast-flying bird that nests on cliffs and engages in hot pursuit of its prey over open country. Large blackish patches on the white underwings distinguishes this from all other falcons. A narrow, black mustache mark, blockish head shape and large eyes are typical. The back and upperwing are medium brown with pale bars and fringes on most feathers and the tail shows light barring underneath. The pale feathering of the underbody is spotted on the belly and barred on the flanks of adults and with streaks on immatures.
SIZE
This is a medium-sized hawk, second-largest in length of the six North American falcons. The Peregrine Falcon is the same length but is slightly heavier while the Gyrfalcon is the largest overall. There is no overlap in size or weight ranges between the smaller male Prairie Falcon and the larger females.
Females average 17 inches (43.2 centimeters) in length while males average 15 inches (38.1 centimeters). Wingspan in females averages 43 inches (109.2 centimeters) and males average 37 inches (94 centimeters). The average weight for females is 1.9 pounds (862 grams) and for males it is 1.2 pounds (544 grams).
MORPHS AND MOLTS
There are no color morphs in Prairie Falcon plumage and the males and females look the same. The back color of individual birds may vary somewhat but not in any way that suggests predictable color morphs. Darker backed birds are always juveniles in their first fall plumage. They alppear darker all the time because they lack pale cross barring on their back. Partial albinism has been reported for this falcon.
Molting occurs annually and following the juvenile plumage, it is the second molt before birds reach the definitive (adult) plumage. This does not change in appearance during subsequent molts. Molting begins with the wing feathers, followed by the body feathers and finally the tail feathers. In Wyoming and Colorado, molt begins in late May and is complete by early October.
SPECIFIC DESCRIPTION
It should be noted that sexes are similar in adult plumages. However, females show a slatey cast on the back that may not develop to the same extent as in males. As well, females have noticably darker underwing patches (on axillars and median coverts) than males.
Adult - Perched
HEAD
- top of head variably gray-brown with dusky streaks
- whitish cheek area between eye and brownish "ear patch" on side of head
- throat and the line above the eye are white
- a narrow black mustache extends from below the eye in a downward direction along the chin
- the beak is bluish with a dark tip
- the cere and eyelid are yellow
- the eye is dark brown
BODY
- the underparts are pure white with dark spots on the breast and belly and barred feathers on the flanks
- many feathers of the back and upper wing coverts are light tan in color with dark brown or sooty patches in the center
- the effect is a darkish back with many light tan cross bars
- slatey-bluish cast develops by second year which is difficult to detect in the field
WINGS
- the upper sides of flight feathers are very dark with light tan to orange-rusty bars
- the wingtips do not reach the tip of the tail in perched birds
TAIL
- upper side has a brownish cast but can vary from gray to rusty colored
- about 10 transverse dusky bars occur on the upper side and they increase in extent with age - the tip is white
- the underside is whitish with incomplete pale banding
LEGS
- the legs and feet are yellow and the talons are black
- whitish leg feathers have dark spots
Immature - Perched
HEAD
- pattern much the same as in adult but softer overall
- the top of the head is somewhat darker than adult
- pale eye stripe may be more prominent
- the beak is bluish with a dusky tip
- the cere and eye ring are pale bluish
- the eye is very dark
BODY
- the chin and throat are white while the breast and other underparts are creamy in fresh plumage which quickly fades to white
- short, narrow streaks on the breast and belly, wide, long streaks on the flanks
- there are more dark markings than in adults and they tend to merge into blackish areas on the sides
- the flanks are more heavily streaked
- the back is somewhat darker than in adults with the light brown barring lacking
WINGS
- similar to adult plumage
TAIL- the upper surface is darker with more complete barring and the tip is white
- the underside is whitish as in adults
LEGS
- the legs and feet are pale bluish with black talons but they start developing the yellow color
SIMILAR SPECIES
In overall size and proportions, the adult Prairie Falcon most closely resembles the adult Peregrine Falcon, but the latter is much darker-backed, has a significantly broader mustache stripe and lacks the dark patches in the axillars and median coverts of the wing underside. Many immature Peregrine Falcons have an identical narrow mustache but the light area on the face, behind the eye on the Prairie Falcon is distinctive. Light colored Swainson's Hawks may have a superficially-similar face pattern but they lack the white area between the eye and the ear patch as seen in Prairie Falcon.
OTHER NAMES
The Prairie Falcon has also been called the "Bullet Hawk."
ETYMOLOGY
Falco is of Latin origin and means "sickle." Many authors believed it to be in reference to the shape of the beak but it has been suggested that the name more properly refers to the shape of the talons. the species name mexicanus refers to Mexico - the country from which the Prairie Falcon was first described. Prairie describes the type of countryside preferred by this species, which is essentially open, hot and dry places.
MYTHOLOGY
There is no known mythology for this species in North America
VOICE
Vocalizations are very similar to those of the Peregrine Falcon but slightly higher pitched. The alarm call is a series of "kik" notes given by both sexes. Literature references describe various sounds such as screaming, whistling, whining, yelping and cackling as being part of the repertoire. Voices of all of the larger falcons are felt to be similar in basic structure and function.
