Quantifying Potential Nesting Habitat and Maximum Spatial Carrying Capacity for Bald Eagles in Florida

We used species distribution modeling to map the spatial distribution of potential nesting habitat for Bald Eagles (Haliaeetus leucophalus) across the State of Florida, USA. First, we related bald eagle nest occurrence data to environmental factors with a maximum-entropy (Maxent) model. Second, we used the resulting habitat suitability map from the Maxent model to quantify spatial carrying capacity for nesting pairs in the state. A combination of land cover variables (e.g., proportions open water, canopy coverage, distance to evergreen forests, and proportion wetlands), bioclimatic variables (isothermality, precipitation, temperature), elevation, and anthropogenic variables accurately predicted bald eagle nest occurrence (AUC = 0.9). We estimated that a total of roughly 2,500 breeding pairs could simultaneously occupy high quality nesting territories in Florida, assuming all known nests were occupied and any additional nests were located at least 1 km from their nearest neighbors. This total is roughly 1,000 more than the documented number of breeding pairs, suggesting there may be previously unidentified breeding pairs or potentially unoccupied nesting habitat available in Florida. The suitability map and spatial carrying capacity estimates could be used to guide future nest searches and habitat restoration efforts.