American kestrel (Falco sparverius)


       A large captive colony of approximately 250 pedigreed American kestrels (Falco sparverius) is maintained at the Avian Science and Conservation Centre. Kestrels have been used extensively by researchers from all over the world in laboratory studies involving aspects of toxicology, behaviour and physiology. They also proved useful as a model species to develop management techniques, e.g artificial insemination, forced renesting, for the endangered Peregrine falcon (F. peregrinus) raised at the centre during the 70s and 80s.  

       The kestrel nests in most rural and urban areas in North America. Two subspecies are known to exist: F.s. sparverius and F.s. paulus. F.s. sparverius weighs 85-140g (the female being approximately one-third heavier than the male), are 9-12 inches in length and have a wingspan of 20-24 inches. In general, American kestrels have rusty-red head caps, backs and tails, and a black and white facial pattern. Males have blue-grey wings, while the females have brown wings.
This species can easily be sexed by plumage after 12 days of age, and becomes sexually mature during their first spring.  They breed readily in captivity.  Ninety percent of randomly selected pairs lay one egg every two to three days to produce a clutch of five eggs (they will renest if their first clutch is lost). Their eggs range from white to a light cinnamon, variably covered with small dots and splashes of various shades of brown: they are 35 x 29 mm in size on average. 

       The breeding season usually begins in early April in temperate regions, peaks at approximately 13.5 hours of daylight and is strongly influenced by the length of day. Eggs take 28-30 days to hatch, the sex ratio at hatching is 1:1 and nestlings take between 25-30 days to fledge.  In the wild, kestrels take insects, mice and occasionally small birds. The McGill colony is sustained on an ad libitum diet of frozen-thawed day-old cockerels, usually one to two per day. Although kestrels do not require water for drinking, they especially enjoy bathing.


Return to ASCC Homepage

© 2003 Avian Science and Conservation Centre
McGill  University, 21,111 Lakeshore Rd.
Ste-Anne-de-Bellevue, Québec,  Canada H9X 3V9
Phone: (514) 398-7760     Fax: (514) 398-7990