PATTERNS OBSERVED IN AN INTENSIVELY MONITORED RAPTOR COMMUNITY IN NORTHWEST WYOMING

Abstract Raptors around the world have experienced marked declines from a variety of reasons in recent decades. We continued an effort that began in the 1940s to monitor an entire raptor community in a protected landscape in northwest Wyoming. Our goals were to describe basic information on nesting raptor ecology such as nesting substrate use, nest re-use, nest switching, and nest persistence, and to track changes in the raptor community over time. We searched a 31.1-km2 area intensively for all nesting raptors and surveyed a 841.1-km2 study area primarily for Red-tailed Hawks (Buteo jamaicensis) and Common Ravens (Corvus corax), but recorded other nesting raptors and corvids when observed. In 2001–2002 and 2014–2015, we located and monitored 182 nesting attempts during intensive monitoring in the smaller study area. Between 1992 and 2015, we located and monitored an additional 984 nesting attempts in the larger study area. Nests were used by 14 raptor species and 2 corvid species. Nests built in trees accounted for 92.5% of all located nests. Most nests, 75.3%, were used only 1 y, although nest re-use varied from 1 to 13 y. When a nest was reused, it was most commonly used by the same species. From the 1940s through 2015, very little change occurred in the raptor community with the exception of a slight decrease in Red-tailed Hawks and a slight increase in Common Ravens. Our results inform a basic understanding of nesting raptor needs and support the idea that protected landscapes may be effective tools for conserving species like raptors.