Population ecology of the bald eagle (Haliaeetus leucocephalus) in Florida Bay, Everglades National Park, Florida, 1959-1990

Abstract

Using aerial census techniques, I collected data on the population, reproduction and nesting habits of Bald Eagles in Florida Bay, Florida, for three consecutive breeding seasons (Oct - Mar, 1987 - 1990). For analysis I consolidated my data with those collected by Robertson et al. between 1959 and 1986 for a total of 26 seasons. The breeding population of Bald Eagles in Florida Bay has been stable since censuses began in 1959. However, numbers of subadult eagles in Florida Bay have declined sharply since the early 1960’s. Breeding density was apparently limited by territoriality. Nesting success was positively correlated with early commencement of nesting, number of active breeding territories and the history of individual breeding territories. Success was negatively correlated with the amount of rainfall during the breeding season. Most (87%) nesting failures occurred during the incubation stage. Nearly all nests were built in mangrove [Laguricularia racemosa, Avicenia germinans and Rhizophora mangle) trees and of these more than half were dead. The success of a nesting attempt was independent of changes in nests or nest sites.