Landscape-level habitat use by brown-headed cowbirds in Vermont

摘要: We studied the distribution of brown-headed cowbirds (Molothrus ater) in a forested landscape central Vermont to better understand effects forest disturbance on occurrence this species New England. mapped 702 patches where chronic created permanent openings, such as pastures, lawns, and ski areas, recent logging had temporary openings. surveyed 67 randomly selected for cowbird presence during 1992-93 breeding seasons; we detected 46% patches. used logistic regression develop predictive models from variables that described each patch terms size, shape, position relative livestock areas other disturbances. The model best predicted by (75-80% correct classification) consisted area patch, distance closest number within 7 km patch. From model, concluded large (?= 9.8 ha) were either chronically disturbed, or close near high concentration most likely contain cowbirds. employed grid-based geographic information system (GIS) procedure map probability across study area. illustrates small (? = 4.0 ha), remote openings are unlikely attract Vermont.