This project uses the environmental disturbance generated by the BP Deepwater Horizon oil spill in the Gulf of Mexico to assess the relative importance of density vs. trait-mediated effects in regulating populations of the brown pelican. The investigators will combine post- and pre-spill data to quantify the effects of different levels of oil exposure on population density and ecologically relevant traits, and on the population-level consequences of different exposure scenarios. By providing a detailed analysis of how traits such as foraging behavior combine with population density to influence the dynamics of a top predator, the study will further our understanding of the ecological factors that regulate population dynamics and the long-term, non-lethal effects of major anthropogenic disturbances.
The brown pelican was completely extirpated from Louisiana in the 1960's and only recently removed from the Endangered Species list. Since then, it has become a culturally important symbol of ecosystem resilience in the Gulf of Mexico. The project will raise public awareness about how exposure to environmental contaminants may affect this and other colonial nesting seabirds affected by the oil spills, and results will inform conservation practitioners and wildlife biologists about effective management of these populations. The proposed research will also provide training to one undergraduate student and one female post-doctoral fellow.
The brown pelican is perhaps the best-recognized species from the Gulf of Mexico region, and has become a culturally important symbol of this ecosystem’s resilience. It is the state bird of Louisiana (The Pelican State) but was temporarily extirpated from the state in the 1960’s and only recently removed from the Endangered Species list. Our project used a newly developed technology – GPS tags – to track movement the brown pelican in unprecedented detail. In doing so, we obtained novel data on foraging ecology of this species, which was previously poorly known because of logistical difficulties associated with quantifying their movements. Our findings include information on home range size, patterns of activity at various temporal and spatial scales and stages of the breeding cycle, and insights into relationships between sex, body condition, nest stage, and foraging behavior. We found no differences in movement between the sexes, but we did observe that physiological condition early in the breeding season interacts with nest stage to influence foraging behavior, such that birds in better condition early on fly shorter distances during the most energetically demanding nest stage, nestling provisioning. Our results improve our understanding of how physiology may impact movement ecology. Further, they provide useful information to conservation biologists and managers interested in protecting brown pelicans and other waterbird species. This work also provides a foundation to link movement patterns to the underlying distribution of prey (in this case, the Gulf menhaden), which we view as the next step in this research program. We have disseminated our findings through publications and presentations, including the Audubon Society, and provided training to a post-doctoral fellow and graduate and undergraduate students.
