A survey of Golden Eagles (Aquila chrysaetos) in the western US: Mid-winter 2017
Western EcoSystems Technology, Inc., Nielson RM, DiDonato GT, Mcdonald LL. 2017. A survey of Golden Eagles (Aquila chrysaetos) in the western US: Mid-winter 2017. Cheyenne, Wyoming
A report for the U.S. Fish & Wildlife Service that provides region-wide transect survey data for Golden Eagles in the Western USA. We flew aerial line transect surveys using distance sampling and mark-recapture procedures to estimate Golden Eagle (Aquila chrysaetos) abundance in 4 Bird Conservation Regions (BCRs) in the western United States between 17 January and 17 February, 2017, on 206 transects totaling 16,483 km. The study area consisted of BCRs 9 (Great Basin), 10 (Northern Rockies), 16 (Southern Rockies / Colorado Plateau), and 17 (Badlands and Prairies). We observed 265 Golden Eagle groups within 1,000 m of 115 transects for a total of 325 individuals: 139 adults, 76 unknown immatures (not adults), 96 unknown adults (not juveniles), and 14 of unknown age. We did not classify observed Golden Eagles as either sub-adults or juveniles during the winter survey. We estimated that a total of 11,381 Golden Eagles (90% confidence interval: 8,698 to 14,906) were within the Great Basin (BCR 9) during the survey period, a total of 11,012 (90% confidence interval: 7,181 to 15,851) were within the Northern Rockies (BCR 10), a total of 3,248 (90% confidence interval: 2,063 to 4,709) were within the Southern Rockies / Colorado Plateau (BCR 16), and a total of 13,983 (90% confidence interval: 10,016 to 19,241) were within the Badlands and Prairies (BCR 17). These estimates do not include Golden Eagles that were potentially occupying military lands, elevations above 3,048 m (10,000 ft), large water bodies, or large urban areas.