Long-term Population and Colony Dynamics of Brown Pelicans (Pelecanus occidentalis) in Rapidly Changing Coastal Louisiana, USA

Coastal Louisiana has suffered from dramatic coastal land loss. Following translocations to Louisiana in the late 1960s, Brown Pelican (Pelecanus occidentalis) colonies were annually surveyed between 1971 and 2010 using aerial methods. The goals of this study were to describe long-term Brown Pelican colony dynamics, investigate physical changes to nesting islands via satellite imagery, and relate colony dynamics to physical island changes. Thirty Brown Pelican colonies were found, with a mean colony persistence of 5.5 years. Following exponential growth up to 2000, nesting plateaued, declined sharply in 2006 primarily due to land losses following the intense 2005 hurricane season, and stabilized at lower levels until 2010. From 1998 to 2010, island size decreased by a mean of 68.7%, with 10 of the islands vanishing entirely. Colony size was positively correlated to island size. Colonies did not shift between State regions, but appeared to shift within regions. To persist in Louisiana, Brown Pelicans will need to continue adjusting to a changing coastline, as well as planned coastal restoration projects. Future monitoring of Brown Pelicans in Louisiana may provide insight into their adaptive responses to changing availability and suitability of nesting island habitat.