Movement ecology studies have depended upon using GPS-GSM telemetry to track year-round movements of golden eagles. As part of research efforts by CSG and collaborations with other scientists, we have put together large datasets of eagle locations so we can assess flight patterns and habitat use of Golden Eagles throughout the State of California.
Habitat use of Golden Eagles in the Mojave Desert
Habitat use by Golden Eagles nesting in the Mojave Desert shows they are most likely to interact with renewable energy developments during the breeding season, when their home ranges are smallest and most tied to areas surrounding nest sites. At other times of the year, these same eagles move outside of the desert to mountainous areas.
Influences of human development on raptor abundances during winter in southern California deserts
Abundances of raptors and other predatory birds in the Sonoran and Mojave Deserts of California are influenced by human development. Some species, such as Common Ravens and Red-tailed Hawks, are associated with human development and have increased in abundance in recent decades. Other species, such as Golden Eagles and Prairie Falcons, showed decreased abundance over these same time periods.
Topographic influences of flight altitude above ground level for Golden Eagles
Risk of colliding with wind turbines is partially defined by how high Golden Eagles fly above ground level (AGL). For example, eagles that fly above wind turbines are not at risk of colliding with them. We found that flight AGL was dependent upon the topographic characteristics of the landscape over which Golden Eagles flew and that some of these relationships differed among regions in California. Golden Eagles tend to fly higher over smoother terrain that occurs at lower elevations throughout the state. These characteristics influence development of thermal updrafts used by soaring eagles. They tend to fly lower over topographic settings where orographic updrafts develop, and these settings differed among regions within the state. These patterns mean risk of Golden Eagles colliding with wind turbines can be partially explained by the topography where turbines are built, and that risk will differ regionally.
We began studying the movement ecology of Golden Eagles in California in 2012 to assess potential interactions between eagles and renewable energy. In California, expansion of renewable energy development has been driven by both state and federal initiatives to increase clean energy production. However, renewable energy has the potential to affect Golden Eagles through collisions between eagles and wind turbines and removal of eagle habitat. Our research has provided information for the Desert Renewable Energy Conservation Plan for southern California Deserts as well as understanding potential risk of eagle collisions with wind energy developments throughout California.
Braham, M., T. Miller, A. E. Duerr, M. Lanzone, A. Fesnock, L. LaPre, D. Driscoll, and T. Katzner. 2015. Home in the heat: Dramatic seasonal variation in home range of desert golden eagles informs management for renewable energy development. Biological Conservation 186:225–232.
Duerr, A. E., T. A. Miller, L. Dunn, D. A. Bell, P. H. Bloom, R. N. Fisher, J. A. Tracey, and T. E. Katzner. 2019. Topographic drivers of flight altitude over large spatial and temporal scales. The Auk: Ornithological Advances 136:ukz002.
Duerr, A. E., T. A. Miller, K. L. Cornell Duerr, M. J. Lanzone, A. Fesnock, and T. E. Katzner. 2015. Landscape-scale distribution and density of raptor populations wintering in anthropogenic-dominated desert landscapes. Biodiversity and Conservation 24:2365–2381.