Habitat Associations and Population Trends of Two Hawks in an Urbanizing Grassland Region in Colorado

摘要: Despite increasing interest in the ecological effects of urbanization, relatively little is known about its grasslands. We examined population trends and habitat associations two predators, rough-legged hawk (Buteo lagopus) red-tailed (B. jamaicensis), a rapidly urbanizing grassland region at western edge North American Great Plains. Count data indicate that populations declined area by nearly 75% between 1971 2003, same time numbers hawks more than tripled. These changes were not part wider regional trends, nor they buffered development an open space system one counties. While human grew steadily over 33-year period, did begin to change significantly until early 1980s, suggesting landscape threshold responses development. Rough-legged remaining 1999 2002 avoided settlements hunted places with tracts treeless grassland. In contrast, selected tall perches trees or on utility poles from which hunt, areas closer buildings roads randomly plots, remained abundant mosaic developed rural agricultural lands. The failure sustain hawk, other bird species characteristic prairie, illustrates challenges conserving fauna apparent hypersensitivity three-dimensional complexity accompanies even modest amounts