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The Montana Cooperative Wildlife Research Unit

The University of Montana

Ross Crandall - M.Sc. Candidate - Wildlife Biology

Co-Advisors: Tom Martin and Erick Greene


Natural Science Building - Room 311

Phone: 406-243-4396




2005 B.S. Wildlife Ecology and Management, University of Wisconsin-Stevens Point.

Project Title

Determining influence of landscape changes on a breeding golden eagle population: 1962-present.

Background and Objectives

Long-term monitoring of species and ecological communities can provide information impossible to obtain otherwise.  Further, evaluating the current population status of a species is difficult without baseline data with which to compare current numbers.  This is especially important for species thought to be declining to determine the reality and extent to which that may be occurring.  During the past 15 years raptor migration counts have documented a decrease in the number of golden eagles, typically from northern latitudes, passing through count sites in the Rocky Mountain region.  While these efforts are invaluable for monitoring population trends, they are unlikely to determine factors resulting in population decline.  In addition, most breeding eagles in this region are non-migratory or do not follow typical migratory pathways so are infrequently included with count site data.  The result is a lack of information on their population status.  By focusing on breeding sites, it is possible to assess the degree of apparent decline on a broader scale and identify mechanisms driving change by determining primary influences on breeding success. 

Beginning in 1962, research efforts were initiated by Dr. John Craighead to evaluate breeding golden eagle territories and productivity in a 3,260 km study area near Livingston, Montana.  This is located in the northern portion of the Greater Yellowstone Ecosystem (GYE), just north of Yellowstone National Park.  The focus of the original study was to determine nesting density, success, productivity, prey selection, effects of pesticides, and provide general information about golden eagle ecology.  Since this initial phase, the GYE has seen a 55% increase in the human population, a diversifying economy shifting away from resource extraction and agriculture, an increase in rural development and transitions in land cover (Hansen et al. BioScience. 2002 (52: 151-162)).  With these and other factors potentially impacting the golden eagle population plus access to the historic dataset, I began the current phase of this project in 2010 under the guidance of Derek Craighead.  The goal of my project is to assess current status of the golden eagle population and examine how changes on the landscape have influenced nesting density, territory occupancy and productivity in the historic study site.

Current Status

I have completed 2 field seasons of data collection prior to beginning the graduate program at the University of Montana and hope to continue for 2 more after defending my research proposal in January of 2012.   For more information on the project, visit the link to Craighead Beringia South.

Special thanks to Derek Craighead and Bryan Bedrosian of Craighead Beringia South for making this project possible.

Natural Sciences Room 205

Missoula, MT 59812