Factors influencing nest-site selection by Spanish Imperial Eagles

We examined nest-site selection by Spanish Imperial Eagles (Aquila adalberti) in Doñana National Park (southwestern Spain) from 1984–1994. Spanish Imperial Eagles are large birds of prey that defend and occupy a territory year-round. Identifying a territory's nest-site characteristics represents a critical step in safeguarding this endangered species' habitat. We measured seven habitat variables describing microhabitat, vegetative composition, land use, and degree of human influence for 73 nest sites averaged for 14 occupied territories and 73 randomly selected sites for 14 unoccupied territories. Our best logistic regression model included two habitat variables representing microhabitat (height of nest tree) and human influence (distance to the nearest urban centre). The logistic regression model correctly classified 78.6% of the occupied and 85.7% of unoccupied territories. This analysis suggests that the presently occupied Spanish Imperial Eagle territories represent the majority of the remaining suitable habitat for this endangered species in and around Doñana National Park. There is an urgent need to create suitable nest sites for Spanish Imperial Eagles that would include tall trees in small tree stands away from intense human activity.