The American Kestrel is the smallest and most widespread of the five falcons regularly seen in North America. It is a regular along the fields of rural Snohomish County. Even though Edmonds is pretty much built up, the kestrel can be seen from time to time in the city, usually around the marsh. It inhabits any kind of open or semi-open habitat, including deserts, farmland, and even forest clearings. When perched, it can be found on fenceposts, utility wires, or tree branches. Nature writer Pete Dunne calls this bird the Wire Falcon because of its propensity to perch on utility wires.
Diet of the American Kestrel is made up of large insects as well as some small rodents, reptiles, and birds. Grasshoppers are its favored prey, but it also eats caterpillars, moths, dragonflies, and beetles. Other prey include small rodents such as voles and mice, sometimes bats, small birds, lizards, frogs, crayfish, and even earthworms. A kestrel begins its hunt by watching from a high perch and then swooping down to catch its prey. If perches are not available, this falcon hovers over a field while watching for prey. It flies into the wind at windspeed, which causes its unique style of hovering. In England, its close relative the Eurasian Kestrel is sometimes called wind hover because of this trait.
In courtship displays, the female will fly slowly with stiff wingbeats, her wings held just below horizontal. The male will make repeated ascents and dives, calling while on the ascent. He also will offer food to the female, passing it to her in flight. The nest site is usually in a cavity in a dead tree or snag, 10-30 feet above ground. Sometimes this species will nest in a dirt bank or on a cliff. In Eastern Washington it might use an old magpie nest. In parts of the country that have lost suitable nest sites, the kestrel will use artificial nest boxes.
Both sexes incubate the 4-6 eggs for about one month. The female remains with the hatchlings for the first week or two while the male brings food to the nest. After that, the female also hunts. The young take their first flight at about one month of age. The parents continue to feed the young for another two weeks. Juvenile kestrels may join groups of young from other nests.
Collective nouns for wildlife often reflect traits of the species. It is not surprising that traditional collective nouns for the American Kestrel include flight, hover, and soar. Johannes Riutta, owner of The Well-Read Naturalist (reviews of natural history books) blog, has devised new collective nouns for a number of raptor species. For the American Kestrel, the smallest of North America’s falcons, he offers “a compactness of kestrels.
The oldest known kestrel was a male,14 years and 8 months of age, when found in Utah in 2001. It had been banded in that state in 1987. While the American Kestrel can prey on smaller birds, it is preyed upon by larger raptors such as Red-tailed Hawks, Northern Goshawks, both Sharp-shinned and Cooper’s Hawks, and Barn Owls. Even American Crows have been known to take kestrels.
Even though it is common and widespread, American Kestrel populations declined by about 50% between 1966 and 2015. Estimates of the population are about 4 million, with 39 percent spending some part of the year in the U.S., 10 percent in Mexico and 13 percent breeding in Canada. Current declines are based on continued land clearing and removal of the dead trees that these birds depend on for nest sites. The species is also losing prey sources and nesting cavities to farming practices that remove trees, brush, and hedgerows. Pesticides can reduce clutch size and hatching success. Pesticides destroy the insects and other small prey that the kestrel depends on. Nonetheless, for now it remains a species of least concern for conservation purposes.
You can hear the repeated calls of an American Kestrel here: http://www.xeno-canto.org/254588.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.