BEHAVIORAL ECOLOGY OF GREY EAGLE-BUZZARDS, GERANOAETUS-MELANOLEUCUS, IN CENTRAL CHILE
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1989
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Abstract
Throughout 1 year we observed the behavioral ecology of Grey Eagle-Buzzards (Geranoaetus melanoleucus) in central Chile. The eagles'' activity period was bimodal, with peaks in mid-morning and mid-afternoon. During the day they spent most of their time flying (except during winter), extensively soaring in thermal and wind updrafts, rarely using flapping flight. Eagles appeared to select specific physiographic features that favored the presence of updrafts, particularly north- and west-facing slopes and ridge tops. Use of these features apparently was unrelated to prey abundance or vegetative cover. Prey were primarily large-sized small mammals, and secondarily reptiles and birds. Although aggressive, eagles were attacked by a number of species of other raptors. Comparison of the behavioral ecology of eagles and of Nearctic buteonines demonstrated some marked differences, particularly in activity time and habitat use. These differences appear to be related to weather conditions prevailing in montane vs. lowland terrain.