Movement patterns and population structure of the brown pelican

Abstract

Interest in monitoring the population viability of the Brown Pelican (Pelecanus occidentalis) has recently risen in the context of the species' 2009 delisting as endangered, rapid degradation of nesting habitat, and recent oil spills. To assess the Brown Pelican's patterns of movement (across natal colony, nonnatal colony, and noncolony islands), age and sex structure, and survival probabilities, we banded 1177 chicks in Louisiana from 2007 to 2009. In band-resighting surveys within the Isles Dernieres archipelago from 2008 to 2010, we detected 92 of our banded birds. Neither age nor sex appeared to influence where we observed pelicans resting on beaches across the islands, and we found the highest proportions of pelicans at their natal island. Yet few observations of banded birds suggest either movement outside our study area or mortality. Conditions at colonies and proximity to other sites of loafing or colonies may in part explain the disparity in proportions of resightings of individuals banded on different islands. Finally, the apparent probability of survival of one-year-old pelicans was lower than that of two- and three-year olds. Insights into these trends in movement and survival of young Brown Pelicans can improve future management of colony sites. © 2013 by The Cooper Ornithological Society.