Our objective was to estimate demographic parameters and population trends for Swainson's hawks (Buteo swainsoni) breeding in southeast Alberta and southwest Saskatchewan, Canada, from 1972 to 2003. We assembled mark–resighting–recovery histories of 6,606 banded Swainson's hawks for a joint analysis of survival and resighting probability, including band-reporting rate and fidelity of animals, following Burnham's joint resighting–recovery model provided in program MARK. Our best-fitting survival model specified age-related variation in survival, resighting probability, and fidelity, and it specified age-by-temporal variation in nestling survival and adult resighting probability. From estimated survival rates and previously published data on reproduction, for the period 1973–1996 we estimated the population's finite rate of increase, λ, to be 0.996 (95% CI: 0.945–1.057). We believe that population limitation of Swainson's hawks is primarily related to the influence of prey availability on brood size and nestling survival. Despite indications of recent population declines, we conclude that Swainson's hawks breeding in western Canada are not currently in need of special management action.
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Vol. 70 • No. 5