Success of captive-rearing for a threatened shorebird

Abstract

Captive-breeding and -rearing programs have been widely used for the conservation and recovery of imperiled species, and the success of such programs should be rigorously evaluated. In this study, we assessed the success of captive-rearing for a threatened shorebird, the snowy plover Charadrius nivosus, by comparing the survival and reproductive success of captive-reared and wild-reared individuals on the central California coast from 2001 to 2010. We used mark-recapture analysis, implemented in the program MARK, to estimate apparent annual survival (ϕ) and encounter occasion detection probability (p) from capture and sighting data of marked plovers. We compared 3 measures of reproductive success (hatch rate, fledge rate and juveniles fledged per year) using stratified randomization tests based on individual breeding histories where captive- and wild-reared plovers were matched for age, sex and year. Captive- and wild-reared snowy plovers had similar apparent survival and reproductive rates and paired with mates of similar age in their first breeding year. The only exception was that captive males after their first breeding year had lower fledging rates than males from the overall population, but this did not affect the annual productivity rate. We conclude that releasing captive-reared individuals is a valuable part of ongoing efforts to restore the snowy plover population in California, and is also useful in cases where plover nests may need to be salvaged to protect them from oil contamination or other catastrophic events.