Status of a Northern Population of California Brown Pelicans

Abstract

In the Southern California Bight (SCB), Brown Pelican (Pelecanus occidentalis californicus) breeding populations were apparently historically stable. They are again increasing after pollution-related declines in the late 1960's and early 1970's. This increase has been bolstered by recruitment into the breeding population of pelicans fledged outside the SCB area, but populations did not increase significantly until after improvements in reproduction of the SCB population itself. Nesting chronology is apparently related to food availability. Early-nesting, whether at Anacapa Island or Islas Los Coronados, usually confers a reproductive advantage. This advantage varies at each location; breeding populations reassort each year, apparently in response to variable food supplies. Shifting between two major breeding colonies in the SCB is apparently a response to a changing food supply distribution. Annual variations in normal (as opposed to pollution-affected) breeding population size result partly from changing proportions of the available adult population that actually breeds.