Prairie Falcon

On the wild side—September, 2013

by Tina Mitchell

Falcons are birds of prey that are most noted for their long, pointed wings and their stunningly swift and powerful flight.  One species that breeds in our area is the Prairie Falcon.  Standing 15 – 18” tall, its back is a pale, grayish brown and its chest and belly are white with some spotting that is heaviest on the flanks.  Its most distinctive field mark is probably the dark “mustache” slash running vertically down its light face—often the darkest point on the bird.  Males and females look alike, although the male (as is true in most raptor species) is often considerably smaller than the female.  This hint isn’t much help for most of us, though, unless they’re sitting side by side—which rarely happens.  These falcons of the arid country range over the western half of North America, from southern Canada to central Mexico.  In winter, they may move east and sometimes even south.

Find a Prairie Falcon during breeding season and you’re mostly likely near a good source of ground squirrels, cottontails, and other small mammals, which provide fat-rich calories for raising its ravenous young.  During winter, they often switch to hunting songbirds, especially Horned Larks and Western Meadowlarks.  Although these are the preferred items on the menu, Prairies will capture a variety of other species, up to the size of grouse and jackrabbits, as well as lizards and larger insects.  When you’re hungry and as good a hunter as a Prairie Falcon, nearly any unsuspecting creature that moves can become a meal.  They often hunt by flying fast and low over ground with low vegetation, taking prey by surprise.  They can also dive steeply from the air (called “stooping”) or pursue and overcome birds in flight.

Pairs arrive on breeding territories in Feb. or March, with incubation in our area beginning around mid-April.  The female usually lays 5 eggs (range 2 – 6) in a shallow depression on a ledge or in a pothole; she handles most of the incubation tasks for the 31 days before the eggs hatch.  The male brings her food and may temporarily sit on the eggs while she eats.  Once the chicks hatch, the male delivers prey to the nest and the female rips pieces off to feed the young.  When the nestlings reach about 4 weeks old, she may join in the hunting chores to feed the growing youngsters.  The young leave the nest about 5 – 6 weeks after hatching and rely on the parents for another month or so, as they learn to hunt independently.

Falco mexicanus is the Prairie Falcon’s scientific name.  Both the genus name and the term “falcon” come from the Latin falx, which describes an agricultural implement with a curved blade or a hook in reference to the strong hooked talons found on all falcons.  Mexicanus refers to the nominate specimen (the specimen used to create its name), which came from Mexico.  And “prairie” refers to the areas of low vegetation that this falcon uses for hunting.

The Prairie Falcon’s larger cousin, the Peregrine Falcon, was severely impacted by the use of the pesticide DDT.  Prairie Falcons escaped this fate, but they have been seriously affected by other human activities.  Their nestlings have been favorites of falconers, who take the young from nests, raise them, and train them to hunt for them.  In the past, Prairie Falcon nests (also called “eyries”) have been raided to the point of no breeding success for several years in a row.  Even eyries that weren’t directly raided but were located in popular rock-climbing and hiking areas often failed to produce young, simply because the adult birds were so disturbed by humans in the area.  In light of these problems, Colorado wildlife agencies and conservation groups throughout the nation have initiated nest-monitoring programs to protect existing eyries.  Happily, the 400-500 pairs thought to be breeding in North America in 1994 have now grown to an estimated total of 5,000-6,000 breeding pairs.

You can learn a bit more about this species and see some photos here.

Photo by Bill Boulton, via Wikimedia Commons.