Tag: American Kestrel

Size dimorphism in mated pairs of American Kestrels

American Kestrel (Falco sparverius) Science Article 3 abstract The degree of dimorphism between males and females has been examined in a number of raptors (Storer 1966, Reynolds 1972, Balgooyen 1976, Snyder and Wiley 1976), but few studies have reported the amount of dimorphism between mated pairs of birds. If the maintenance of a size difference […]

EASTERN SCREECH-OWL HATCHES AN AMERICAN KESTREL

American Kestrel (Falco sparverius) Science Article 16 abstract An Eastern Screech-Owl (Otus asio) was found incubating her own egg and that of a Southeastern American Kestrel (Falco sparverius paulus) in late March 1995. Three owlets and the kestrels uccessfully hatched in early May; all appeared normal. The kestrel was not present in the nest box […]

Plasma corticosterone in American kestrel siblings: effects of age,hatching order, and hatching asynchrony

American Kestrel (Falco sparverius) Science Article 18 abstract Although it is well documented that hatching asynchrony in birds can lead to competitive and developmental hierarchies, potentiallygreatly affecting growth and survival of nestlings, hatching asynchrony may also precipitate modulations in neuroendocrine developmentor function. Here we examine sibling variation in adrenocortical function in postnatally developing, asynchronously hatching […]

Haemoproteus tinnunculus in the American Kestrel (Falco sparverius)

American Kestrel (Falco sparverius) Science Article 2 abstract Unspecified species of Haemoproteus have been recorded from American Kestrels in Texas, Colorado and Panama; and Haemoproteus elani de Mello, 1935 has been recorded from kestrels in Oklahoma. However, there are no published identifications of Haemoproteus tinnunculus in this avian host in North America. This investigation reports […]

Hypothermic tolerance in an embryonicAmerican kestrel (Falco sparverius)

American Kestrel (Falco sparverius) Science Article 4 abstract Embryos of several bird species tolerate acute hypothermia. However, the extent to which it can be toleratedby wild species living under natural conditions is poorly documented. At a single American kestrel (Falco sparverius)nest 15 days into incubation, we observed a 21-h bout of egg neglect by the […]

Conservation Assessment for the American Kestrel in the Black Hills National Forest, South Dakota and Wyoming.

American Kestrel (Falco sparverius) Science Article 14 abstract This report assesses the biology and conservation status of the American kestrel (Falco sparverius) in the Black Hills National Forest of South Dakota and Wyoming. The goal of this assessment is to assimilate historical and current literature on the kestrel to provide managers and the general public […]

Possible relationships between morphology, territoryquality, and skin color of American Kestrels

American Kestrel (Falco sparverius) Science Article 10 abstract Carotenoid-based coloration of skin and plumage has been found to be correlated with individualquality in many species of birds during the breeding season. However, less is known about the possible role of thesesignals during the nonbreeding season, particularly among nonpasserines that defend winter territories. AmericanKestrels (Falco sparverius) […]

ISOLATION OF A HERPESVIRUS FROM AN AMERICANKESTREL WITH INCLUSION BODY DISEASE

American Kestrel (Falco sparverius) Science Article 13 abstract A herpesvirus was isolated from the liver of a captive-bred American kestrel(Falco sparverius) which had died of inclusion body disease. Initial isolation wasachieved in chicken embryo fibroblasts after three blind passages. Cell-adapted virusproduced a distinct rounding of CEF cells within 24 to 48 h. Biologic and serologictests […]

Regulation of Yolk-Androgen Concentrations byPlasma Prolactin in the American Kestrel

American Kestrel (Falco sparverius) Science Article 12 abstract The concentrations of maternally derived androgens in the yolks of avian eggs vary within and among clutches, but a mechanistic basis for this variation has not been elucidated. We investigated in the American kestrel, Falco sparverius, whether changes in plasma-prolactinconcentrations induced by changes in photoperiod and food […]

Copulatory behaviour and paternity in the American kestrel:the adaptive significance of frequent copulations

American Kestrel (Falco sparverius) Science Article 11 abstract The adaptive significance of repeated withinpair copulations is not well understood. We analysed thecopulatory behaviour of 16 pairs of solitary-nesting American kestrels, Falco sparverius, in southernQuebec (Canada), and the achieved reproductive success (paternity) of 21 kestrel families determined byDNA fingerprinting, in terms of four hypotheses. (1) The […]