Southern Bald Eagle Productivity and Nest Site Selection

Abstract

Productivity and nesting habitat of the southern bald eagle (Haliaeetus 1. leucocephalus) in north-central Florida were analyzed. The productivity of 109 active nests over a 4-year period (1973-76) was 1.14 young/nest, and for 78 successful nests was 1.59 young/nest. Thirty-four sites examined in 1976 were within 3 km of water and were preferentially located in flatwoods and hardwood swamps. Most nests were in dominant pines, and nest trees tended to be located along ecotones. No correlation (P > 0.05) was obtained when production of young was regressed on distance from water or distance between nearest neighbors. Production was independent of habitat within 0.5 km of 61 nests studied during the 1976 nesting season. Production of young was independent of habitat alteration and road use at distances of 0.0-0.5, 0.5-1.0, and 1.0-1.5 km from active nests. J. WILDL. MANAGE. 43(3):585-594 Although bald eagles formerly ranged throughout North America, stable populations are presently found only in Alaska, Florida, Wisconsin, and probably Minnesota and the central Canadian provinces (Sprunt et al. 1973). The greatest number of breeding bald eagles in the contiguous United States occurs in Florida with concentrations in Everglades National Park and the Ocala National Forest vicinity (Sprunt et al. 1973). Populations in other parts of Florida have declined (Howell 1968). Causes of bald eagle population declines include pesticides, chiefly the chlorinated hydrocarbons, and habitat loss (Sprunt 1969). Since 1972, use of DDT has been banned giving rise to optimism that improvement in production of young may occur. Increasing human population and suburban sprawl have greatly reduced bald eagle habitat in recent decades either directly by destruction of nesting trees or indirectly by disturbance in the vicinity of nesting trees (Sprunt and Ligas 1966). Because of increased mobility of Florida residents and tourists, areas that were once remote are now regularly visited by people in boats and motor campers. Nesting habitat of this fish-eating raptor is also being infringed upon by increasing numbers of waterfront cottages (Sprunt 1969). Knowledge of specific habitat requirements of bald eagles has become important in formulating effective management strategies, particularly since pesticides may cease to be an important limiting factor. The objectives of this study were to determine productivity of bald eagles in north-central Florida and to relate productivity to selection of nesting habitat. Financial support was provided by the School of Forest Resources and Conservation, University of Florida; the National Wildlife Federation; and the Florida Game and Fresh Water Fish Commission. We thank R. R. Roth, U.S. Forest Service and S. A. Nesbitt for their cooperation and encouragement. L. D. Harris and J. A. Cornell provided statistical advice. We are also grateful to D. W. Johnston, W. R. Marion, S. Postupalsky, and I Contribution 1565 of the Journal Series, Florida Agricultural Experiment Station, Gainesville, FL 32611. 2 Present address: U.S. Forest Service, San Bernardino National Forest, Big Bear City, CA 92314. J. Wildl. Manage. 43(3):1979 585 This content downloaded on Wed, 12 Dec 2012 21:25:34 PM All use subject to JSTOR Terms and Conditions 586 BALD EAGLE NESTING IN FLORIDA -McEwan and Hirth Goinesville 0 NEWNANS Putnam