Big Days at the End of Fall Raptor Migration

November 20th, 2012

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What a fantastic fall raptor migration! This fall we counted 212 more raptors than last fall. Our red-tail hawk numbers nearly matched our 2011 total, making up 32% of raptors counted. Rough-legged hawk numbers jumped up four times higher than 2011. The 25 broad-winged hawks might be the highest among Montana raptor sites. The hawk-owl that buzzed our observation site on September 21st will remain an exciting memory for all in attendance.

We pushed the end date back one week due to a record high count of 218 on November 7th, one day before the scheduled finish date. It was also the eve of a major weather disturbance that lasted two days, and when it cleared we had another big day on November 10th with 104. When an arctic front pushes southward MPG Ranch seems to get big migratory events. We witnessed a similar event at the end of last years fall count. The large raptors that were either coming from the far north, or just taking their time moving south, became persuaded by the cold front. When a late season storm like this shrouds the mountain ridges, has a north wind, and leaves a line of sun along the Bitterroot valley, the results are a raptor highway. Red-tail hawks, rough-legged hawks, golden eagles, and bald eagles, made up 87% of all raptors counted in the last two weeks of surveys.

Thank you Cherin Chapman and Daniel Harrington for their keen eyes and great company during the long, and smoky, season. Also, thank you Adam Shreading and William Blake of Raptor View Research.

Raptor Counts: Nov. 15, 2012

Species

Week Total

11/9-11/15

Month Total

Season Total

Turkey Vulture

0

0

23

Osprey

0

0

28

Bald Eagle

29

89

114

Northern Harrier

12

41

203

Sharp-shinned Hawk

0

5

377

Cooper's Hawk

0

2

134

Northern Goshawk

1

2

20

Broad-winged Hawk

0

0

25

Red-tailed Hawk

76

272

766

Rough-legged Hawk

23

94

253

Swainson's Hawk

0

1

8

Ferruginous Hawk

0

2

5

Golden Eagle

5

33

91

American Kestrel

0

3

190

Merlin

1

2

9

Peregrine Falcon

0

3

8

Prairie Falcon

0

2

11

Unknown Accipiter

0

0

27

Unknown Buteo

9

33

59

Unknown Falcon

0

0

1

Unknown Eagle

0

1

1

Unknown Raptor

3

13

22

Total:

159

598

2375

Raptor Counts: 2011/2012 Fall Totals

Species

2011 Total

2012 Total

Turkey Vulture

50

23

Osprey

45

28

Bald Eagle

58

114

Northern Harrier

137

203

Sharp-shinned Hawk

383

377

Cooper's Hawk

167

134

Northern Goshawk

10

20

Broad-winged Hawk

6

25

Red-tailed Hawk

776

766

Rough-legged Hawk

58

253

Swainson's Hawk

9

8

Ferruginous Hawk

5

5

Golden Eagle

84

91

American Kestrel

225

190

Merlin

6

9

Peregrine Falcon

4

8

Prairie Falcon

9

11

Unknown Accipiter

44

27

Unknown Buteo

46

59

Unknown Falcon

2

1

Unknown Eagle

5

1

Unknown Raptor

34

22

Total:

2163

2375

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.