Effects of Double Brooding on Productivity of Crested Caracaras

Abstract

-During at least one of three nesting seasons, 13 breeding pairs of Crested Caracaras (Caracara plancus) in south-central Florida made a second nesting attempt following a successful first attempt. Ten pairs successfully fledged young in both attempts. Only early nesting pairs attempted a second brood. Most double-brooded pairs fledged their first brood before 1 March. The time interval between first and second nesting attempts was positively correlated with the number of young fledged from the first attempt. Clutch size declined between first and second nests of double-brooded pairs, and second nests failed more often, but pairs that attempted two broods in a season fledged significantly more young than did single-brooded pairs. Estimates of survivorship to recruitment were higher for young from first broods than for young from single or second broods. Although the influence of double brooding on annual productivity seems only marginal, this strategy likely persists because of the potential increase in fitness incurred by individuals that successfully fledge two sets of young in a single nesting season. Received 24 February 1997, accepted 19 March