Nest-Site Selection and Success of Louisiana Bald Eagles

摘要

Mating pairs of Haliaeetus leucocephalus (Bald Eagle) nest during winter in Louisiana, and numbers of nests have increased exponentially since the mid-1970s. Active nests have remained relatively concentrated within the south-central and southeastern part of the state, in an area primarily consisting of inland swamps, coastal marshes, and barrier islands, which is referred to as the Basin. However, as the number of nests continues to grow, it is expected that nesting will continue to expand geographically into new habitats. In order to manage an expanding population, it is imperative to first determine parameters that influence nest-site selection. To evaluate site selection and success, we conducted GIS-based analyses to evaluate geographic variables such as proximity to water, landcover, human activity, and other nests. We compared 387 active nests from the 2007-2008 winter nesting season and 1935 random sites, which represented available habitat for site selection. Our results suggest that success of a nest within the Basin was not greatly influenced by the physical characteristics around a site, but sites with the highest probability of being selected for nesting generally had a higher probability of success. Initial selection of a nest site was most influenced by distance to road, number of houses per km(2), and landcover within 3 km, but the influence of these variables varied between sites within and outside the Basin. Our results should assist managers in making informed decisions about effects of future developments, conservation activities, and human use on current and future suitable nesting habitat.