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NATURE HAPPENINGS - January 2003

A Prairie Spirit
by Damian Fagan

In Pete Dunne’s book Hawks in Flight he describes the western-dwelling prairie falcon as the “...butte-haunting ghost of a falcon, a prairie wraith.” Synonymous with open country, prairie falcons utilize sandstone cliffs or towering buttes that rim or interrupt these sparse grasslands or shrublands for nest locations. Unless you are in their nest site vicinity, one’s view of these prairie spirits is often a quick sighting of a bird rapidly moving away.

Prairies are large, pale falcons. Their brown backs are a contrast to the whiter underparts of the body and wing linings. One key identifying field mark are the dark axillaries - the “armpit feathers” - located where the wings meet the body, and are best visible while the bird is in flight. The light brown mustache mark, which many might think more of as a sideburn, offsets a small white patch on the birds cheek (hence the mustache description). And the hooked or falcate shape of the claws is the reference for the Latin word falco meaning falcon.

Like all falcons, the females are larger than males. On average, female prairies are larger than the males by a couple of inches. When observing a pair of falcons in courtship displays, it is easy to separate the sexes by their size.

Prairies may initiate their breeding season in February or March. This is an excellent time of year to view these raptors since the birds are very vocal and active in their courtship displays. Loud wailing cries or shrill whistling calls may easily betray their position; however, I remember times of scanning a canyon wall section by section unable to locate the wailing bird. Perhaps those rocky ledges went deeper than I expected.

Some of my past bird work included monitoring prairie falcon nest sites for disturbances or the production of young. These nest sites were as different as the prey that these birds fed upon. Some sites were isolated rocky towers with the birds utilizing a wide ledge or small alcove. Other alcove or ledge sites were located on large cliff walls, either high up on the cliff face or within 10' of the ground. Even abandoned raven nests were used for prairie falcon nests.

As birds of open country, prairie falcons employ a couple of hunting strategies. One, which is shared by many birds of prey, is to perch atop a prominent outcrop, telephone pole or canyon rim, and visually search for prey. The other method, which prairies use, is to fly low over the ground and let the element of surprise flush some unsuspecting prey into action. One time I watched a prairie falcon scare up a green-winged teal from an old stock pond, then proceed to chase down the duck after a dizzying chase that relied upon G-force maneuvers, Stuka dives and barrel rolls. No wonder the U.S. Air Force adopted this bird as their official mascot.

Birds are not the only prey that prairies will go after. Small mammals like ground squirrels, young prairie dogs or field mice, complement a diet of lizards and grass-hoppers. Preferred are ground-dwelling birds like horned larks, meadowlarks and mourning doves. Even burrowing owls have been known to become a prairie falcon’s meal.

So as February buffers the transition period between winter and spring, a birder’s to-do list may want to include some outings into the drier portions of the outback to listen/look for these fleeting spirits of the West.

 

 

 

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