Common raven populations have increased more than 300 percent over the last 40 years in the western United States. Along with the eggs and nestlings of greater sage grouse, ravens also prey on the federally endangered Desert Tortoise, the endangered San Clemente Loggerhead Shrike and the California Least Tern.
In addition to proximity to transmission lines, ravens in the study area selected nest sites that were in close proximity to edges formed between sagebrush and land cover types associated with direct human disturbance such as introduction of non-native species, or fire. The degree of this fragmentation averaged 2.4 times greater at nest locations in the study area than at random unaltered sites. The scientists believe that in contrast to continuous sagebrush stands, edges enable the ravens to more readily detect prey and depredate nests of other bird species.
The authors summarized that among all variables, the distance to transmission lines, distance to edge and amount of edge had the greatest relative importance to ravens in selecting nesting locations. However, the findings in the study indicated that ravens also preferred nesting areas with non-native vegetation and they avoided junipers more so than on random sites.
The results of these findings pointed to further increases in raven abundance in formerly natural sagebrush steppe following alterations made by people, specifically those associated with energy development and an expanding electric grid. The authors state, "Such an increase likely poses an increased threat to sagebrush steppe species subject to raven depredation, including sage-grouse for which eggs and young are consumed by ravens."
WCS Northern Rockies Program Coordinator Jeff Burrell said, "Sagebrush steppe is one of the most
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Wildlife Conservation Society