Ovulation Synchrony as an Adaptive Response to Egg Cannibalism in a Seabird Colony

The predominant cause of egg loss in a large Galucous-winged Gull (Larus glaucescens) colony in Washington is cannibalism. Previous work demonstrated the occurrence of every-other-day clutch initiation synchrony in dense areas of the colony during years when cannibalism was most frequent, suggesting that synchrony is an adaptive response to cannibalism. Here we show that (1) the initial egg laid in a nest is more likely to be cannibalized than subsequent eggs, (2) an egg is most likely to be cannibalized within the first 24 hours after it is laid, and (3) the odds that an initial egg is cannibalized within the first 24 hours decreases with an increase in the total number of initial eggs laid on that day. These findings support the hypothesis that clutch initiation synchrony functions as an adaptive response to cannibalism by increasing the odds that an initial egg will survive during its most vulnerable period