50-Year Golden Eagle Nesting Trends In South-Central Montana

Scientific Disciplines
Biological Sciences - Terrestrial
golden eagle
south central montana
golden eagle nesting
Volume 17, No. 1-4

50-year golden eagle nesting trends in south-central 
Ross H. Crancall, Craighead Beringia South, Kelly, Wyoming 83011, crandall.ross@gmail.com 
Bryan Bedrosian, Craighead Beringia South, Kelly, Wyoming 83011
Derek Craighead, Craighead Beringia South, Kelly, Wyoming 83011
Golden Eagle (Aquila chrysaetos) migration counts in the western North America have 
shown a significant negative trend in recent years.  However, the causes of these declines 
are unknown and it remains unclear if declining migration counts correlate to a declining 
population or changes in migratory behavior. Long-term research on nesting Golden Eagle 
populations is lacking and is needed to properly assess the current Golden Eagle population 
status in many areas.  In 1962, intensive monitoring efforts were initiated in a roughly 
1200-mi2 study area in south-central Montana. The objectives were, among other things, to 
determine density and productivity of Golden Eagles. This area was re-surveyed in the mid 
1990s to begin looking at long-term population trends.  In 2009, we initiated a multi-year 
effort to investigate potential changes in the nesting trends in the same study area over a 
half a century. The data collected to date indicate an increase in the nesting density, similar 
nest success rates, and a decrease in productivity when compared with both the 1960’s and 
1990s studies. The longevity of data collected in this study area allows for one of the longest-
term comparisons for Golden Eagle nesting density and success in the West and provides 
invaluable insights into the status of nesting Golden Eagles in this region.