This is our smallest falcon and the most familiar and widespread falcon in North America. They are found in the United States year round. They are frequently seen perched on overhead power lines, trees, and fence posts while searching for prey. If you see a bird hovering over a field, it is likely an American kestrel looking for its next meal. You will find them in meadows, grasslands, deserts, parks, cities and suburbs.
The American kestrel is the most colorful of all raptors – the male has slate-blue head and wings, with a rusty-red back and tail. The female’s wings are a reddish brown. Both sexes have a “moustache” – the black vertical stripes on the sides of their pale faces. They are about the size of a mourning dove but with a larger head; longer, narrow wings, and a long square tipped tail. Kestrels are 8-12 inches long with the female being larger. Wing span is 20-24 inches and they weigh only 2.8-5.8 ounces.
Being one of the smallest birds of prey, they are prey for larger birds such as Red-tailed Hawks, Barn Owls, American Crows, and Sharp-shinned and Cooper’s Hawks.
They eat mostly small insects, some small mammals, birds and reptiles. They quickly dispatch their prey by severing the spinal cord at the neck. Grasshoppers are a favorite and give the American Kestrel its nickname – grasshopper hawk. They will also eat dragonflies, moths, and caterpillars. They like to hunt from a high perch, watching intently for prey and then swooping down to catch dinner. If there is no place to perch, they will hover over a field facing the wind and watch for prey. Sometimes they pursue and catch insects, small birds or bats in flight. And since like most birds, they can see in ultraviolet light, they use this ability to see the urine trails that voles leave on the ground conveniently pointing the kestrel to its next meal. Kestrels will cache extra food in grass clumps or tree roots to save for leaner times or just to hide food from thieves.
American kestrels nest in cavities and nest boxes. In the mid-west on I-35, there is a nest box for kestrels nearly every mile. Kestrels readily adapt to human-made nest boxes and will return each spring, do a bit of housekeeping and start the next generation. They do not use nesting material, no fluff for these baby birds. If there is loose material in the box, cavity or crevice, the female will just hollow out a depression.
The male courts the female by flying high, calling and then diving. He brings food for the female and passes it to her during flight. The female lays 3-7 eggs and both sexes help to incubate. Incubation is long – 28-31 days, and then it is another 28-31days before the young take their first flight. Parents take good care of the fledged youngsters by feeding them for an additional 12 days.
Due to removal of dead trees from open land, the kestrel is losing nesting sites. There has been a 50% decline between 1966 and 2015. Pesticides destroy the insects, spiders and other small prey these birds depend on. Nest boxes have helped some populations start to recover. If you would like to install a nest box to help these birds, nest box plans can be found here - http://nestwatch.org/learn/all-about-birdhouses/birds/american-kestrel/.
The oldest American Kestrel was found in Utah, banded in 1987 and was 14 years, 8 months old when found again in 2001.