An Imperial Beach Hidden Gem and Bird of the Week, the "American Kestrel"
Apr 20, 2017 01:35PM
● By Paul Spear
An Imperial Beach Hidden Gem and Bird of the Week, Bryan Brillhart Photography present the “Dig IB” Bird of the Week, the "American Kestrel"
“Dig Imperial Beach” Bird of the Week, the “American Kestrel ”
This week’s “Bird of the Week” is the American kestrel (Falco sparverius), sometimes colloquially known as the sparrow hawk, it is a small falcon, and the only kestrel found in North America. Counts of migrants suggest declining numbers in the northeast in recent years, but numbers elsewhere are still healthy. In open country it is commonly seen perched on roadside wires, or hovering low over a field rapidly beating wings, waiting to pounce on a grasshopper. Kestrels nest in cavities in trees, but in places where there are few large dead snags to provide nest sites, they may rely on nesting boxes put up for them by conservationists.
Kestrel habitats are in open country, farmland, cities, and wood edges. They will inhabit any kind of open or semi-open situation, from forest clearings to farmland to deserts, wherever it can find adequate prey and some raised perches. In breeding season, they may be limited to habitats that also provide appropriate nesting sites. In winter, females may tend to be found in more open habitats than males.
Kestrels hunt mostly by watching from a high perch, then swooping down to capture prey. Sometimes, especially when there are no good perches available, they hover over fields to watch for prey. They may pursue and catch insects, birds, or bats in flight. Individual kestrels often specialize on one particular kind of prey.
Kestrel diet consist mostly of large insects, but also some small mammals, birds, reptiles. Grasshoppers are among the favored prey, but many other large insects are taken, including beetles, dragonflies, moths, caterpillars, and others. They also feed on mammals, including voles, mice, and sometimes bats, small birds (sometimes up to the size of a quail), lizards, frogs, earthworms, spiders, crayfish, other items.
During courtship displays, the female flies slowly with stiff, fluttering wingbeats, the wings held
just below horizontal. Males repeatedly fly high, calling, and then diving. Males bring food for the female, passing it to her in flight. Nest site is in a cavity, usually in dead trees or snags, sometimes in a dirt bank or cliff, or in an old magpie nest. In the southwest, they often nest in holes in giant cactus’. They also use artificial nest boxes. Sites are usually 10-30' up, but may be at any height.
Females lay 4-6, rarely 2-7 eggs that are white to pale brown, usually spotted with brown and gray. Incubation is by both parents, usually between 28-31 days. Females remain with young most of time at first, while males bring food. After 1-2 weeks, the female hunts also. Age of young at first flight is about 28-31 days. Parents continue to feed their young up to 12 days after fledging. Later, these juveniles may gather in groups with young from other nests.
I spotted a female kestrel on the power lines along the trail in the estuary this week scouting for prey, and then hovering over the prey before diving. They are an interesting bird to watch. Look for this bird and other species in our own Tijuana Estuary.
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