P-29 Ovulation Synchrony as an Adaptive Response to Egg Cannibalism in a Seabird Colony

Every-other-day egg-laying synchrony has been demonstrated in the Glaucous-winged gull (Larus glaucescens) colony at Protection Island National Wildlife Refuge ,where cannibalism is the predominant cause of egg loss. Here we show that (1) eggs are most likely to be cannibalized within the first 24 hours after they are laid, and (2) the odds that an egg is cannibalized within the first 24 hours decreases with an increase in the number of eggs laid on that day. This suggests that egg-laying synchrony functions as an adaptive response to cannibalism by maximizing an egg’s chance of survival during its most vulnerable period

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

Every-Other-Day Clutch-Initiation Synchrony as an Adaptive Response to Egg Cannibalism in Glaucous-Winged Gulls (Larus glaucescens)

Sea surface temperatures (SST) in the Pacific Northwest of North America rose 1 °C during the last half of the twentieth century. Cannibalism, a behavior observed in diverse taxa, is often associated with low food supplies, which for marine animals can be precipitated by high SSTs. In an 8 year study, we found that in years of higher sea surface temperatures, Glaucous-winged Gulls (Larus glaucescens) breeding in a colony in Washington State, Salish Sea, USA, tended to exhibit higher rates of egg cannibalism by males, higher levels of every-other-day clutch-initiation synchrony by females, and longer egg-laying seasons than in years of lower SST. Clutch-initiation synchrony increased the odds that an egg survived cannibalism and may serve as an adaptive response to egg cannibalism. Short-term climate and resource fluctuations associated with El Niño Southern Oscillation (ENSO) events may select for behavioral plasticity in marine organisms, allowing long-lived individuals such as marine birds to switch between alternative life history tactics. The implications for long-term SST warming, however, remain unknown

Data for Henson et al. 2016

These data are archived for the paper Adaptation to short-term ENSO fluctuations may provide tipping points for populations subjected to long-term climate change by Henson et al., submitted. Additional files: Supplementary Figure 1 | Sample plots on Violet Point, Protection Island National Wildlife Refuge, Washington, USA. The larger colony extends throughout much of the spit