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Falcons
So, What is a Falcon? Falcons and Humans DOW Working for Wildlife Viewing Sites How to Tell Falcons from Hawks and Eagles

So what is a falcon? Falcons are raptors, or birds of prey, and though related to the hawks and eagles, they belong to a separate family — Falconidae. Falcons are found throughout the world, except for Antarctica and some islands. The archetypal falcon is a hunter of birds, plummeting down upon its prey in a high-speed dive, called a stoop, and slashing or knocking prey from the air. By contrast, buteo hawks like the red-tailed typically soar in the air or sit on a high perch searching for prey on the ground. They drop down on prey and make the kill on the ground. Accipiters such as the sharp-shinned and Cooper's hawks hunt prey in the forest, darting between trees or flying suddenly out from hiding to grab a bird or squirrel. Falcons kill using both their bill and their feet, seizing prey in their talons, then biting the back of the animal's neck. Falcons have notched bills, an adaptation for this killing bite. Hawks and eagles primarily use their talons to crush and pierce their prey. While eagles, osprey and hawks build bulky nests of sticks, falcons don't build nests at all, often laying their eggs on bare cliff ledges or in tree cavities, occasionally using the old nests of ravens and other birds. Some species, such as kestrels, regularly use nest boxes.

Three falcons nest in Colorado—the American kestrel, the prairie falcon and the American peregrine falcon subspecies. Arctic peregrine falcons, another subspecies, migrate through Colorado.

If any one bird epitomizes the falcon family, it is the peregrine. Even its name, which means wanderer, implies something untamed and free. This sleek and beautiful falcon inhabits wild country of cliffs and canyons, nesting on remote ledges. Though nicknamed "duck hawk," peregrines have never been a threat to waterfowl. They hunt all types of birds, including flickers, swallows and swifts, songbirds, shorebirds and pigeons. To see a peregrine stooping on prey is to witness one of nature's spectacular feats. Peregrines are the fastest creatures on earth, capable of aerial dives reaching as much as 200 mph. See DOW Working for Wildlife in this issue for a discussion of efforts to recover the American peregrine falcon, an endangered species.

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From left to right (heads in profile, only): American kestrel, merlin, prairie falcon, and peregrine falcon. (Drawings are not proportional.)

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While peregrine falcons aren't common in our state, prairie falcons live throughout Colorado, ranging from prairie to alpine tundra. They nest on bluffs and cliffs and hunt over surrounding open country. Prairie falcons are similar in size and appearance to peregrines, though slimmer and more brown, with a thinner "sideburn" on the cheek. Prairie falcons don't always hunt in typical falcon fashion. They course low over open terrain, surprising and flushing prey, both bird and mammal, which they grab near or on the ground. Prairie falcons eat a high percentage of mammals; this diet may have protected prairie falcons from the impact of accumulated pesticides which so greatly harmed peregrines. But prairie falcons face other threats. They are declining in Colorado due to urban development of their habitat, and growing human disturbance. A few decades ago an estimated 300-400 prairie falcon pairs nested in the state. DOW raptor biologist Jerry Craig notes there has been a 5-10% decline in nesting sites due to loss of habitat to urbanization.

There's one falcon, at least, we hopefully don't need to worry about. The American kestrel is a common bird throughout much of Colorado, though you may have passed one perched on a phone wire or weed stalk a hundred times without realizing that robin-sized bird was a tiny falcon. Kestrels are strikingly marked and handsomely colored. Males are gun-metal blue, rusty-red and buff, with a red cap. Female kestrels are mainly reddish, with lighter underparts. Both have two distinctive streaks, or "sideburns," down each cheek. Many people know kestrels by their old name, sparrow hawk, though considering its food choices, the kestrel might better be called grasshopper hawk Kestrels eat a great many grasshoppers and insects in spring and summer, relying in winter on mice, voles and shrews. They occasionally kill a small bird. Though they occasionally stoop on prey in classic falcon fashion, kestrels more commonly use their own hunting technique. They hover eight or 10 feet above the ground on rapidly beating wings, the tail fanned and dropped slightly like a rudder to help maintain position. Then they drop down and grab their prey with their talons. The kestrel's high-pitched killy-killy-killy call is familiar in open country.

Kestrels are the most common and widespread raptor in North America. Kestrels nest throughout the U.S. and Canada, though not above the Arctic Circle. Unlike other falcons, kestrels have benefited from the effects of human development. Conversion of woodlands to agriculture created habitat for these open country hunters, and, also unlike some of their falcon cousins, kestrels adapt well to life around humans. They perch on fence posts and telephone wires, learn to hunt behind farm machinery that may scare up prey, visit bird feeders (seeking birds, not seed) and occasionally nest in barns and other structures, including nest boxes.

So next time you venture into a Colorado canyon, onto the prairie or just in a neighboring vacant lot or field, keep your eyes open for falcons!

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The merlin, a small falcon formerly known as the pigeon hawk, migrates through Colorado, occasionally spending the winter in western valleys and on the eastern plains.

The gyrfalcon, the world's largest falcon, is an Arctic species which occasionally wanders south. It has shown up a few times in northeastern Colorado in winter.

The aplomado falcon is a very rare falcon of Mexico and southern Arizona and Texas. It is being reintroduced along the Texas Gulf Coast. This falcon does not inhabit Colorado.

The crested caracara, an interesting bird also inhabiting Mexico and southern Arizona and Texas, is more vulture-like than falcon-like in its appearance and habits. There are no records of the caracara in Colorado.

Next: Falcons and Humans

(The information contained in this issue of Colorado's Wildlife Company was accurate at the time of original publication. Situations and circumstances described, staff positions, contact information, and dates of some events may have changed in the interim. Present knowledge and understanding of biological and behavioral facts and information may also be different, now, than presented here.)