10-22-14 Bird Field Note

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10-22-14 Bird Field Note

October 22, 2014

Kate Stone and the Bird Crew's Field Note documents the first Peregrine Falcon raptor capture of the season, a Pileated Woodpecker caught during banding, and Saw-whet owl tracking from the ground and air.

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Bird Field Note Owl Banding, Shrubby Draws, Songbird Banding, Raptor Surveys Kate Stone 10/22/14

We wrapped up our Northern Saw-whet Owl migration study. We captured 41 owls and put telemetry units on 38 of them. We hypothesized that owls would use the Bitterroot River floodplain as a travel route, because our banding station is on the floodplain and this landscape feature offers continuous vegetative cover the whole length of the Bitterroot Valley. Instead, most owls traveled through the foothills of both the Bitterroot and Sapphire Mountains.

Many of the owls exhibited stopover behavior, staying in the same general area for several days in a row. This behavior may be related to their nocturnal feeding habits; they need to balance both feeding and migrating south at night.

Owl #1104-01730 made the biggest moves of any owl we tracked. We banded it at 11:30 PM on 9/30. Its molt pattern indicated a hatch-year bird.

We found a knobby protrusion on one of the wing bones of Owl #1104-01730. It looked like an old fracture that had healed. The owl showed no signs of impaired mobility.

After spending two days roosting within a mile of the banding station (1), Owl #1104-01730 moved 11 miles south to the Lee Metcalf National Wildlife Refuge, where it roosted in a pine along one of the public nature trails (2). From there, it moved approximately 22 miles to private land in the foothills of the Sapphire Mountains, east of the town of Hamilton (3). After we detected it in the same general area for almost a week, we feared the owl had lost its transmitter. We were therefore surprised to detect the owl 26 miles farther south, in the Piquett Creek drainage near the West Fork of the Bitterroot River (4).

William uses the airplane to lead a flock of geese south.

The MPG Ranch maize maze, as seen from the air.

Bird numbers continued to drop. Though Sheep Camp still exhibited relatively high species diversity, many of the documented species were resident.

Flocks of American Goldfinches foraged on the seeds of curly dock (Rumex cripsus). Song sparrows cleaned up the seeds that dropped to the ground.

Northern Shrikes returned. This one lurked near the goldfinch feeder at the Top House.

During our final week, we saw a significant drop in the number of captures; we captured 188 birds this week compared to 389 the previous week. We had our busiest day on Monday, capturing a total of 49 birds between all three stations. The capture rate progressively decreased throughout the week. Of the three stations, mid-elevation Sheep Camp had the most birds, followed by the floodplain and then West Baldy Ridge. We captured mostly Rubycrowned Kinglets, Dark-eyed Juncos, White-crowned Sparrows, and Song Sparrows. Low capture rates suggest that fall songbird migration is reaching its conclusion.

Song Sparrows are found throughout most of North America, and depending on the population, they can be residents or medium-distance migrants. Because birds from northern latitudes likely migrate through western Montana, we don’t know if we are capturing resident birds or migrants.

We captured this Steller’s Jay at the high-elevation ridge station.

On our last day of banding, we caught this Pileated Woodpecker. We often see them but rarely catch them in our nets.

We counted many fewer raptors this week: 280 compared to 914 last week. The lack of Turkey Vultures makes up the bulk of this difference. We expect Red-tailed and Roughlegged Hawks to dominate daily counts for the rest of the season.

We banded 10 raptors of five different species. We caught the majority of birds at our lower site on Indian Ridge. Falcons continue to make up a surprisingly high proportion of our total captures this season; accipiters typically account for the vast majority of captures at raptor banding sites across North America.

Tyler releases the adult male Peregrine Falcon.

Last winter we outfitted a Harlan’s Hawk with a GPS transmitter. Much to our surprise, we saw it again on October 12, making a pass at the pigeon at the Indian Ridge trapping station. The journey from its summer territory in northwestern Canada to the MPG Ranch took just over one month. Over the last couple days the hawk has moved south of MPG.

The blend of light brown and darker feathers on this Merlin’s back help us identify it as a second-year bird.


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10-14-14 Bird Field Note