The Outdoor Journal by Kyle Carroll
Their official name was changed to “American Kestrel” years ago, but I still prefer the old fashioned “Sparrow Hawk.” Here's how Cornell's All About Birds describes them: “North America’s littlest falcon (about the size of a morning dove) the American Kestrel packs a predator’s fierce intensity into its small body. It's one of the most colorful of all raptors: the male’s slate-blue head and wings contrast elegantly with his rusty-red back and tail; the female has the same warm reddish on her wings, back, and tail. Hunting for insects and other small prey in open territory, kestrels perch on wires or poles, or hover facing into the wind, flapping and adjusting their long tails to stay in place.”
American Kestrels eat mostly insects and other invertebrates, as well as small rodents and birds. Common foods include grasshoppers, cicadas, beetles, and dragonflies; scorpions and spiders; butterflies and moths; voles, mice, shrews, bats, and small songbirds. American Kestrels also sometimes eat small snakes, lizards, and frogs. And some people have reported seeing American Kestrels take larger prey, including red squirrels and Northern Flickers.
Unlike humans, birds can see ultraviolet light. This enables kestrels to make out the trails of urine that voles, a common prey mammal, leave as they run along the ground, sort of like highlighters under a black light show up for our eyes.
American Kestrels normally hunt by day. You may see a kestrel scanning for prey from the same perch all day long—or changing perches every few minutes. A kestrel pounces on its prey, seizing it with one or both feet; the bird may finish off a small meal right there on the ground, or carry larger prey back to a perch.
Kestrels compete over the limited supply of nesting cavities with other cavity-nesters, and sometimes successfully fight off or evict bluebirds, Northern Flickers, small squirrels, and other competitors from their chosen sites.
Although it is one of the most common falcons in North America, Kestrels have declined by about 50% between 1966 and 2015. Current declines stem from continued clearing of land, the loss of grassland and felling of the standing dead trees these birds depend on for their nest sites.
You can help Kestrels by putting up nest boxes and leaving dead trees with cavities standing. When you are cutting firewood, cut a green tree instead and let the firewood season in the sun. Lots of cavity nesters will appreciate it.