Gradients in breeding Brown Pelican foraging radius, chick condition, and diet across the Northern Gulf of Mexico
Juliet S. Lamb, Patrick G.R. Jodice
Wildlife and Fisheries Biology (College of Agriculture, Forestry and Life Sciences)
Unlike many seabirds, the Brown Pelican (Pelecanus occidentalis) relies on coastal habitats for both breeding and foraging. Although pelicans may benefit from supplemental feeding and from prey aggregations around energy installations, they are also vulnerable to contaminants exposure, experience disproportionate oil spill mortality, and represent an important planning and mitigation target. Recent contamination events, notably the Deep Water Horizon spill, have highlighted the need to understand how pelicans use the marine environment; however, published data on Brown Pelican movements are extremely limited. During summer 2013, we fitted 63 breeding adult Brown Pelicans with GPS transmitters at 6 colonies across the northern Gulf of Mexico. We also measured 3-4-week-old chicks at each colony and obtained diet samples from adults and chicks. Preliminary results indicate that breeding-season foraging radius of adults increased from east (Florida Panhandle) to west (southern Texas), while chick body condition declined along the same gradient. Diet composition also differed between colonies: although menhaden (Brevoortia patronus) predominated in all regions, Florida diets contained a higher variety of prey species than central and western areas. This information will guide further investigations into how diet, individual characteristics, environmental factors, and anthropogenic development influence pelican demography and year-round movement patterns.