Final Report: Golden Eagle Migration Survey 2018
The 2018 Golden Eagle Migration Survey atop the Big Belt Mountains wrapped up at the end of October, with yet another day of snow below the 7000’ mark. Access to the site had become marginal days before, and this final storm would close off the main road. With our U.S. Forest Service partners, we completed a total of 26 survey days between September 5th and October 30th, recording 2,292 individual migrant raptors representing 16 raptor species.
Broken down, we have recorded 1,510 Golden Eagles, 216 Sharp-shinned Hawks, 86 Cooper’s Hawks, 95 Red-tailed Hawks, 41 American Kestrels, 44 Northern Goshawks, 93 Bald Eagles,18 Peregrine Falcons, 28 Northern Harriers, 12 Broad-winged Hawks, 8 Prairie Falcons, 9 Merlin, 6 Turkey Vultures, 6 Osprey, 4 Swainson’s Hawks, and 1 Ferruginous Hawk. The remainder were 32 unknown species simply recorded to family.
This spectacular eagle-viewing site saw peak numbers during the 2nd and 3rd weeks of October, and this year’s high count of 349 Golden Eagles occurred on October 18th after the passing of a cold front a few days before. In the eight survey days surrounding that peak, 962 Golden Eagles (64% percent of those counted in 2018) were counted migrating past the site.
The 2018 count proved to be roughly more similar in numbers to the 2017 count than the first two seasons. In 2017, 2,929 individual migrant raptors were counted during 41 survey days, and 2,159 of these were Golden Eagles. (74% percent of migrants counted in 2017). Though Golden Eagle passage rates were similar in all years, much higher numbers of all raptors were counted in 2015 and 2016 with a total of 4,318 and 4,389 respectively. But these numbers represent a quick glance at the total data. We continue to crunch the age and sex-specific species observations and weather data were able to collect in order to compare years in detail.
Autumn storms have pushed us past another fall migration survey season, so it is time to turn our binoculars to the Christmas Bird Count and many Red-tailed, Rough-legged, and abundant other hawks posted-up for the winter across Montana.
We wish to thank Helena Lewis & Clark National Forest and Montana Fish, Wildlife & Parks for their partnership on this project, and we look forward to our continued presence at the site.
Click here to check out the daily count data.
Thank you to the Helena Lewis & Clark National Forest and generous donors for support on this project!