Colonially breeding seabirds: Predators or prey?

The evolution of aggregation in seabirds is usually attributed to predation pressure, although many authors have argued for the role of foraging constraints to be considered. Discriminating between factors that result in group living and characteristics arising from group living has been regarded as an insoluble problem; yet it is possible to test the predictions of the different models proposed to explain colonial nesting. The resulting explanation suggests that seabird aggregations have evolved in order to utilize a dispersed and unpredictable food supply. As such, colonial nesting leads to increased vulnerability to predation, rather than being a strategy adopted to combat it.