Characteristics of Bald Eagle Nest Sites in Oregon

Abstract

We studied the characteristics of 201 bald eagle (Haliaeetus leucocephalus) nest sites in the Douglas-fir (Pseudotsuga menziesii), mixed-conifer, and ponderosa-pine (Pinus ponderosa) forest types in Oregon. Most (84%) nests were within 1.6 km of permanent water and were usually in the largest, most dominant trees in the stand. Ponderosa pine and Douglas-fir were the most frequently used species for nest construction. Characteristics of nest trees and surrounding forest stands were variable, depending on forest type and other local factors. Nest trees and forest stands at sites unaltered by logging or other human disturbance were larger (older) than those produced by short rotation and even-aged forest management. Mean productivity of eagles nesting in the mixed-conifer and ponderosa-pine forest types was lower at sites altered by logging or other human disturbance versus unaltered sites, and productivity was negatively correlated with proximity to clearcuts, main logging roads, decadence of nest trees, and nonrecreational activities. Recently used nests in mixed-conifer forests had fewer recreational facilities and roads in proximity than old nests in the same territory, suggesting a shift from human activities. We recommend minimum nest-tree and forest-stand characteristics for 3 forest types that are based on old- (2300 yr) and uneven-aged management. Size of areas for nest-site management should be 50-250 ha with size and shape depending on surrounding vegetation, topography, and eagle behavior. Human activities within 800 m of nests should be restricted from 1 January to 31 August, and clearcut logging, road building, hiking trails, and boat launch facilities should not be allowed within 400 m of nests.