Lifetime Reproductive Output of Female Sparrowhawks

SUMMARY (1) The number of fledglings reared in a lifetime was determined for a sample of 142 female sparrowhawks. These females were representative, in terms of longevity, of the study area population during a 13-year period. (2) They raised between zero and twenty-three young during their lives, the number varying primarily with longevity, as long-lived females in general raised more young than short-lived ones. Lifetime production was also greater in longer-winged females (assumed to reflect larger body-size), and in females that had been raised in the study areas than in those which had moved in from elsewhere. It did not vary with type of natal or breeding habitat. (3) The number of fledglings reared by individuals correlated with the number subsequently recruited to the breeding population.