POPULATION RECOVERY OF THE EASTERN BROWN PELICAN FOLLOWING ITS EXTIRPATION IN LOUISIANA

Abstract

We report on the exponential growth of the Eastern Brown Pelican (Pelecanus occidentalis carolinensis) in Louisiana, following its extirpation in 1963, and its subsequent reintroduction (1968–1980). This population growth pattern is remarkable since the Brown Pelican exhibits low fecundity, a long life span, and is considered largely nonmigratory in the Gulf of Mexico. To understand the regional changes in breeding numbers of Brown Pelicans in the northern Gulf of Mexico, we investigated the long term trends of the other subpopulations in Florida and Texas. The Florida subpopulation of Brown Pelicans has exhibited a stable-limit cycle, but within the last decade the number of nesting birds has declined while the number of nesting colonies has steadily increased. The number of Brown Pelicans in Texas now exceeds estimates prior to the time pesticides caused reproductive failure of the subpopulation. The Louisiana subpopulation now equals or exceeds its historical (pre-pesticide) numbers. Although local recruitment can account for the exponential growth of Brown Pelicans in Louisiana, we believe that dispersal from colonies outside of Louisiana may have augmented the growth of its nesting population.