Golden Eagle Nesting Ecology

Beginning in 1962 under the guidance of John Craighead, research efforts were undertaken to examine Golden Eagle Ecology in South-Central Montana. At that time, research was focused on nesting ecology, prey selection and effects of pesticides on the birds. While that alone was incredibly powerful information for the time, it also laid the foundation for what is now the longest running dataset on Golden Eagle nesting trends in all of North America.

In the mid 1990’s, Derek Craighead returned to resurvey the study site his father had been so integral in researching some 30 years prior. Upon his return, Derek documented eagles in many of the historic territories his father’s team had found in the 1960’s and further found similar densities as well as productivity of the birds in this Golden Eagle paradise. At that time, the population in the Rocky Mountain region was thought to be recovered and stable so was of little concern to biologists. But this period also marked the beginning of a decline in the number of Golden Eagle’s passing through known migratory flyways. This was cause for biologists and land managers to start paying closer attention and concern started to build. While migration counts are invaluable for monitoring population trends, they are unable to provide the cause of changing trends. With that in mind, CBS biologists saw an opportunity to continue the research started almost 50 years ago on Golden Eagle nesting demographics in South-Central Montana and collect information that could potentially help mitigate declines of these birds in the Rocky Mountain west.

Beginning in 2010, personnel from Craighead Beringia South embarked on the third phase of the Golden Eagle nesting project. The entire study site was revisited in the spring, during the early nesting period, and locations of current territories and active nest sites were documented. During this initial visit, we were able to document the use of nest sites that dated all the way back to the original survey period meaning birds had been nesting in the same area for at least 50 years! After that initial visit, the crew went back 2 additional times to assess productivity. The number of young entering the population (i.e. productivity) is potentially the most critical factor affecting the population decline and is a missing piece of the puzzle that managers need to make informed decisions. With one year of data under our belt, we’re already looking forward to returning in 2011 to substantiate our findings and add current numbers to the incomparable historic dataset we have at our fingertips.