10-18-15 Bird Field Note

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10-18-15 Bird Field Note

October 18, 2015

Debbie Leick compiled the 10/18 bird field note. The note explores owl tracking, raptor migration counts, raptor trapping and tracking, and songbird banding.

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Bird Field Note Owl Tracking, Raptor Migration, and Songbird Banding 10/18/15 Compiled By: Debbie Leick

Northern Saw-whet Owl Migration Study We tracked this Northern Saw-whet Owl to its roost on state land near the ranch. The owl clutched a mouse in its talons.

This owl remained in the same area for two nights to rest and refuel. On the third night, it flew the longest distance of any owl in the study. It left the state parcel and travelled approximately 31 miles to the southern end of the valley.

We recorded 453 migrating raptors, bringing our season total to 2,934. Turkey Vultures, American Kestrels, and accipiter numbers declined this week. We expect that Rough-legged Hawks and other buteos will dominate our counts in coming weeks.

We concluded this season’s raptor trapping on October 1st. We captured 36 raptors of nine species, and deployed satellite transmitters on two Cooper’s Hawks, one Peregrine Falcon, one Prairie Falcon, and three Red-tailed Hawks.

Of the seven raptors with satellite transmitters, only the Prairie Falcon (purple track on map below) seems to have settled on an overwintering site.

During week seven of fall migration banding, we captured 276 birds. This decrease in total captures and species diversity indicate that migration is winding down. The Ridge was the most productive site, with 102 total captures, followed by Sheep Camp (95) and the Floodplain (76). The most common species captured were Dark-eyed Junco and Rubycrowned Kinglet. Clear skies and breezy, warm afternoons followed frosty mornings this week.

Most male Ruby-crowned Kinglets develop a bright red crown patch, but patch color varies from deep scarlet to yellow. At the floodplain site, we captured a rare variant with an orange crown patch.

We captured this Red-naped Sapsucker at the Ridge site. A red chin indicates a male.

Birds accumulate subcutaneous fat in the fall, which they metabolize during migration. The orange fat contrasts with pink muscle tissue.

Fall foliage.

Previous Field Note

10-06-15 Bird Field Note