Spring Raptor Migration Surges

April 13th, 2012

We had another strong week of raptor migration. With 332 raptors this week, our three-week season total is 954. Turkey vultures have begun their journey, numbering 123. Good numbers of Red-tailed hawks, especially juveniles, continue to travel through the Bitterrroot. Ospreys and accipiters are slowly increasing, and we anticipate their peak in the coming weeks.

Spring weather continues to bring variable conditions on a daily basis. We had everything from hot and sunny, to cold and snowy. The first half of the week had south winds, and the latter half had northwest winds. Our numbers seem to be highest with unstable weather patterns, partly to mostly cloudy skies, and temperatures that provide moderate heat thermals. This is similar to our fall counts. Raptors are difficult to locate and observe in blue skies with excellent thermals.

William scans for raptors.

William scans the skies over Baldy for migrants.

Raptor totals from 3/31/12-4/5/12

Species Totals for: 3/31-4/5 Season

Red-tailed hawk 91 (338)

Rough-legged hawk 20 (93)

Turkey vulture 123 (158)

Osprey 6 (9)

Bald eagle 15 (58)

Golden eagle 11 (83)

Northern harrier 17 (36)

Sharp-shinned hawk 19 (28)

Cooper’s hawk 7 (13)

Northern goshawk 0 (5)

American kestrel 4 (10)

Merlin 1 (1)

Prairie falcon 0 (2)

Unidentified accipiter 2 (11)

Unidentified buteo 6 (72)

Unidentified eagle 5 (13)

Unidentified raptor 5 (24)

Total= 332 (954)

Storms create surges of raptor sightings.

Right before storms like this arrive we tend to see a surge in raptors.

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.