2012 Spring Raptor Survey

March 26th, 2012

We are very excited about the first week of spring raptor migration. We have a new site and bird counts are high!

Last year our survey began from a mid-elevation site that was painfully slow for a few weeks. The weather was cold and wet with snow blanketing the Sapphires into April. Then we discovered that migration at this end of the Bitterroot Valley might spread west from the ranch to the foothills of the Bitterroot Mountains. This year we have a lower survey site, which looks very promising so far. We can now scan up towards Baldy Mountain and the Bitterroots, picking out silhouettes of raptors that were previously camouflaged in the terrain as they flew by at eye level. Birds that are traversing the river bottom are also easier to observe.

Conditions were favorable this week, with partly sunny skies and good winds. We had a couple days of rain, each followed by a sunny day that provided a surge of raptors. On March 22^nd we had 135 raptors, which was close to last year’s high during peak migration in mid April.

rough legged hawk

In addition to migration surveys, Rob Domenech and his crew from Raptor View Research are banding raptors this spring. This rough-legged hawk will eventually migrate north, where it breeds in the arctic. Photo: Eric Rasmussen

Totals for March 15-23, 2012

Red-tailed hawk—107

Rough-legged hawk—26

Bald eagle—24

Golden eagle—41

Northern goshawk—4

Cooper’s hawk—1

Sharp-shinned hawk—2

Prairie falcon—2

Turkey vulture—3

Northern harrier—5

Unidentified buteo—43

Unidentified eagle—8

Unidentified raptor—16

Total=282

For comparison, the only other spring raptor survey in our region (Denver, CO.) had a total of 100 raptors for the period of 3/1-3/23.

About the Author

Eric Rasmussen

Eric received a B.S. in Resource Conservation from the University of Montana in 2000, and soon after volunteered for his first bird research job in the arctic tundra of Alaska. Afterwards he worked for nine years, mostly in western Montana, on bird-related research projects for the U.S. Forest Service.

In 2010, Eric was hired by MPG Ranch as the Bird Research Technician and now conducts breeding bird surveys, raptor migration surveys, and winter bird surveys, as well as participating in other ranch projects such as owl and raptor banding and community field trips. In his free time, Eric enjoys searching for wild mushrooms, playing ultimate Frisbee, and backcountry skiing.