The Effects of Climate Change on Marine Birds, Part II: Population Dynamics and Evolutionary Outcomes

For the past fourteen years, we (along with biologist Jim Hayward) have studied the effects of environmental change on colonial seabirds at Protection Island National Wildlife Refuge, Washington, USA, located in the Strait of Juan de Fuca.

Mean sea surface temperature (SST) in the Strait has increased 1°C since 1950. We have observed changes in seabird behaviors during isolated El Niño events when mean sea temperature is high, and we hypothesize that these changes will become prevalent in the long term as mean SST continues to rise.

Changes include a significant increase in egg cannibalism and changes in reproductive timing, specifically the synchronization of every-other-day egg laying by females. We hypothesize that decreased fish availability associated with high SST is correlated with the rise in cannibalism, and that reproductive synchrony is a response to cannibalism. Simple proof-of-concept models illustrate that these behaviors can be evolutionary stable strategies.

These proof-of-concept models do have serious deficiencies with regard to seabird biology, however, the most significant being the different time scales on which the breeding season occurs and juvenile maturation occurs. We are developing more sophisticated models, based on the simpler models, that can account for this time scale difference.