Fall Migration Research

November 24th, 2014

By: Kate StoneM.S. Avian Scientist

Fall Raptor Migration

Technicians from Raptor View Research Institute and the MPG Ranch counted migrating raptors from September to November. Impressive numbers of Turkey Vultures (1089), Red-tailed Hawks (816), and American Kestrels (310) moved through (Figure 2). Counters also documented 41 Broad-winged Hawks, a species that does not breed in Montana but apparently passes overhead during migration.

Table 1. Raptors counted during 2014 fall migration

A Broad-winged Hawk (left) and an American Kestrel (right) circle above the count site

A Broad-winged Hawk (left) and an American Kestrel (right) circle above the count site.

Fall Songbird Migration

The Avian Science Center set up nets to capture migratory songbirds at three elevations. They captured a total of 2,887 birds. Top species included the Ruby-crowned Kinglet (392), White-crowned Sparrow (195), Cedar Waxwing (190), Yellow-rumped Warbler (183), and the Chipping Sparrow 158.

Avian Science Center technician captured some unusual species, including a Canada Warbler (left) and a White-throated Sparrow (right).

Northern Saw-Whet Owl Migration

MPG Ranch staff captured 38 Northern Saw-whet Owls and used radio telemetry to track their migration route south through the Bitterroot Valley. Most owls travelled through the foothills on the east and west sides of the valley. Many exhibited multi-day stopovers as they migrated. We tracked one owl over 50 miles; its greatest movement in one night was 26 miles.

Northern saw-whet owl migration MPG Ranch staff captured 38 Northern Saw-whet Owls and used radio telemetry to track their migration route south through the Bitterroot Valley. Most owls travelled through the foothills on the east and west sides of the valley. Many exhibited multi-day stopovers as they migrated. We tracked one owl over 50 miles; its greatest movement in one night was 26 miles.

Shrubby Draw Surveys

The MPG bird crew mapped the locations of birds in three shrubby draws for 12 weeks from mid-August until the end of October. We mapped precise locations for 3446 birds of 75 species. Top species included Vesper Sparrow (409), Chipping Sparrow (367), Yellow-rumped Warbler (237), and White-crowned Sparrow (216).

Our surveys revealed both temporal and spatial patterns in songbird migration. For example, our surveys documented early- (e.g., Vesper Sparrow, Chipping Sparrow), mid- (e.g., Yellow-rumped Warbler) and late- (e.g., White-crowned Sparrow, American Robin) season migrants (Figure 1).

Figure 1. Seasonal changes in abundance of six species using shrubby draws during fall migration.

Upcoming Projects

What’s next for the bird crews? MPG Ranch staff will be surveying winter raptors throughout the Bitterroot Valley for the next four months. We will also perform point counts on low-elevation and floodplain sites on the MPG Ranch. We will document winter birds using several shrubby draws. Raptor View Research Institute will be trapping Golden and Bald Eagles beginning in December. We will also be busy planning our projects for next year!

About the Author

Kate Stone

Kate graduated from Middlebury College with a B.A. in Environmental Studies and Conservation Biology in 2000. She pursued a M.S. in Forestry at the University of Montana where her thesis focused on the habitat associations of snowshoe hares on U.S. National Forest land in Western Montana. After completing her M.S. degree in 2003, Kate alternated between various field biology jobs in the summer and writing for the U.S. Forest Service in the winter. Her fieldwork included projects on small mammal response to weed invasions, the response of bird communities to bark beetle outbreaks and targeted surveys for species of concern like the black-backed woodpecker and the Northern goshawk. Writing topics ranged from the ecology and management of western larch to the impacts of fuels reduction on riparian areas.

Kate coordinates bird-related research at the MPG Ranch. She is involved in both original research and facilitating the use of the Ranch as a study site for outside researchers. Additionally, Kate is the field trip coordinator and website manager for the Bitterroot Audubon Society. She also enjoys gardening and biking in her spare time.