Posted by ppeery on April 29th, 2013 in Education and Inspiration, General, Nature/Environment
The American Kestrel
The American Kestrel, Falco sparverius, can be seen in Albemarle County year round. They prefer open habitats covered by short ground vegetation, such as along Plank Road and the fields of Bundoran. It is the smallest and most widespread North American falcon. The specific name sparverius was given to it by Linnaeus because of its mistaken connection with the European sparrowhawk which is in a different genus, Accipiter. The facial pattern is distinctive, with one vertical black stripe across the malar region and another across the auricular area. The male has blue gray wings and a rufous tail with a single broad black band. The female is slightly larger and has rufous wings barred with black and has multiple bands on the tail. In flight it has a characteristic falcon silhouestte with long pointed wings and deep wing-beats.
The kestrel migrates from its northern most breeding grounds in Canada and the northern US to spend the winter in many of the “lower 48” and Central America. In the southern US some individuals are resident year round and some move about in the winter.
Even though kestrels prefer open habitats they need perches and nest trees. They may be seen on braches of large trees or power lines when looking for prey. Occasionally they “hover-hunt”. Insects and small rodents, especially grasshoppers, beetles, mice and voles, are predominant in their diets but small birds and reptiles are eaten. Both sexes will cache uneaten remains and surplus kills in tree limbs fence posts, grass clumps etc for later use.
Kestrels breed and nest in April and May in our area. The male locates potential nest cavities, then escorts the female to them. The female apparently selects the site. They are “obligatory” secondary cavity nesters, using woodpecker excavated holes and natural cavities. Nest boxes are sometimes used, usually when well concealed by vegetation. They prefer cavities surrounded by large open areas with perching areas nearby or along the edges of forests. The female lays 4 to 5 eggs and both parents (predominantly the female) incubate the eggs using incubation patches. After about 28 days the eggs hatch; the altricial young are almost naked. All of the brooding is done by the female; after 8-10 days the young are developed enough to maintain their body temperature during the day and the female stays on the nest only at night.
Density of kestrels in an area varies greatly, as does nesting density. Nesting boxes can increase the density particularly if cavities for nesting are limited. Nesting or roosting boxes can be important for overwintering birds as well. Twentieth century farming practices of large areas of monoculture without hedgerows or edge habitat have reduced Kestrels’ habitat. Nesting boxes have been associated with a reversal of kestrel decline in many areas.
Kestrels have been successfully raised in captivity more than any other native North American “hawk”. Hand-reared kestrel commonly exhibit play behavior and single-sex colonies do not show overt physical aggression.Kestrel’s have 3 main types of vocalizations; the klee call, consisting of 3-6 notes, is most often heard from stressed or excited birds. The whine callis made by both sexes during courtship as well as in response to human disturbance. The chitter call is used by both sexes when interacting with the opposite sex or with other kestrels.
Kestrel vocalizations can be heard:
An excellent site to read more about kestrels and nesting boxes is: