10-20-15 Bird Field Note

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10-20-15 Bird Field Note

October 20, 2015

Eric Rasmussen compiled this bird field note. The note shows Rough-legged Hawks, a Brown Creeper, and Ruby-crowned Kinglets.

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Bird Field Note 10/20/15 Field Observations, Raptor Migration, Songbird Banding Compiled by Eric Rasmussen

A migrant White-throated Sparrow stops in the Northern Floodplain to refuel.

refuel. Small groups of Ruby-crowned Kinglets move through the canopy in waves.

Field trip participants scan the sky for incoming raptors.

Rough-legged Hawks arrive from the far north.

We recorded 137 migrating raptors, bringing our season total to 3,071. The Turkey Vulture flight ended and Accipiter and American Kestrel numbers continue to decline. Our top species for the week include the Red-tailed Hawk, Sharp-shinned Hawk, and Northern Harrier. We expect eagles and Rough-legged Hawks to continue increasing.

Some of our raptors with transmitters reached overwintering areas, while others continue to migrate. A Prairie Falcon and Red-tailed Hawk appear to have settled on wintering grounds in Idaho. The Peregrine Falcon and both Cooper’s Hawks are in Mexico, still travelling south. Two Red-tailed Hawks are also still on the move and following similar paths; one was last located in central Colorado, and the other in Texas.

During the final week of fall migration banding, we captured 157 birds of 22 species, our lowest weekly capture rate of the season. The most common species was Ruby-crowned Kinglet (40 captures), followed by Dark-eyed Junco (35), Golden-crowned Kinglet (18), and Black-capped Chickadee (18). We caught the most birds at Sheep Camp (79 captures), followed by the Ridge (41), and the Floodplain (37).

We captured this young creeper at the Ridge site. Brown Creepers are the only North American member of the treecreeper family Certhiidae.

In previous years, we’ve captured a small number of Black-capped and Mountain Chickadees (below) infected with scaly leg mites (Knemidocoptes mutans), a disease more commonly found in domesticated birds than in the wild. We saw no mite infections this year.

Previous Field Note

10-18-15 Bird Field Note