Survival and causes of mortality in wintering Sharp-shinned Hawks and Cooper's Hawks.

Wilson Bulletin, September, 2005 by Lima, Steven L.; Roth, Timothy C., II; Vetter, William E.

Sharp-shinned Hawks (Accipiter striatus) and Cooper's Hawks (A. cooperii) are important predators of birds in North America, but little is known about their natural history during the winter. Even basic survival information is not well documented in these species and is generally unknown during the winter. Therefore, we examined survivorship and causes of mortality among wintering Cooper's and Sharp-shinned hawks. We radio-tracked 27 Cooper's and 40 Sharp-shinned hawks during 5 winters from 1999 to 2004. Neither species nor sex was a significant covariate of survivorship, but the probability of adult survival (75.4%) over 110 days was significantly higher than that of juveniles (9.4%). Our estimate of adult survivorship is comparable with those published for other accipiters, but...

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