10-07-14 Bird Field Note

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10-07-14 Bird Field Note

October 7, 2014

Eric Rasmussen''s Bird Field Note shows migrating pelicans, Sharp-shinned hawks and Turkey Vultures.

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Bird Field Note Shrubby Draws, Songbird Banding, Raptor Migration Eric Rasmussen 10/3/14

The shrubby draws were quiet this week, with migrant numbers and diversity lower than in past weeks. Tongue Creek had four species and 23 total birds. American Pipits boosted total numbers in both Partridge Alley and Sheep Camp. For the past several weeks, flocks of pipits have roamed the open grasslands, occasionally stopping to forage on the eroded sides of draws.

We caught 327 birds this week, compared to 431 the week before. The week began strong, but captures dwindled as the week progressed. The highest single-day total at any one site was Wednesday 24 September, when we caught 43 birds on the floodplain. We caught more than twice as many birds at Sheep Camp (132) and the floodplain (134) compared to West Baldy Ridge (61) this week. Our most common captures included Ruby-crowned Kinglet (72), Cedar Waxwing (49), Yellow-rumped Warbler (32), and White-crowned Sparrow (31).

Although it is the smallest hawk in North America, a Sharp-shinned Hawk may capture prey as large as an American Robin. Sharp-shinned Hawks have a long tail and rounded wings, making them agile on the wing. Females exceed the weight of males by about 30%.

We have only captured one Marsh Wren during each of the two previous fall banding seasons. We caught this one at first light on the floodplain, while we opened mist nets.

Cedar Waxwings are highly social birds, spending their time in flocks throughout the entire year. It is one of the few North American birds that specializes in eating fruit, although they supplement their diet with insects captured on the wing. While this juvenile wears the black mask typical of adult waxwings, it also displays the brown streaked plumage distinctive of young birds.

Over the week, we counted 682 raptors, including 404 Turkey Vultures. As expected, we observed a big push of raptors before the weekend’s winter weather, with high daily counts of 194 and 246 on the 25th and 26th. We saw fewer birds at the end of the week, as precipitation made it difficult for birds to fly. However, brief breaks in the weather allowed some migrants to pass, including 102 Turkey Vultures on the 28th.

Turkey Vultures form a kettle over the floodplain.

A lone Turkey Vulture is an uncommon sight this fall.

An immature Sharp-shinned Hawk glides low, lured by large flocks of Horned Larks.

Though we only banded five raptors, two of them were new species to the Fall 2014 capture list: a Prairie Falcon and a Northern Goshawk. Inclement weather at the end of the week limited both bird flights and our ability to use our high-elevation blind.

A Prairie Falcon was our first large falcon captured this season.

The prominent tail bands of a Merlin help trappers identify these falcons quickly as they whip through the trapping station.

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10-02-14 Bird Field Note