A laboratory simulation of predator-induced incubation interruption using ring-billed gull eggs

Abstract

Field observations have shown that nocturnal predation may cause nest desertion by adult larids. Such desertion was simulated by exposing laboratory-incubated ring-billed gull eggs to 10 °C at either early, intermediate, or late periods of incubation. Hatchability was not significantly reduced by exposure. However, when eggs classed as 'non-viable at collection time' were eliminated, an increase in embryonic mortality was found to occur in late samples. The mean incubation time of all experimental eggs was slightly increased and the variance of incubation time was significantly greater for groups of eggs that suffered longer exposures at middle and late points in incubation. It is suggested that predator-induced desertion in natural populations may increase embryonic mortality and chick age heterogeneity, which in turn may reduce chick survival.