10-14-13 Bird Field Note

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10-14-13 Bird Field Note

October 14, 2013

The bird crew describes the capture of a rare Tennessee warbler, the serious look of a young northern goshawk, and the perfect raptor migration storm.

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Male Mountain Bluebird

A yellow-rumped warbler, above, and a dark-eyed junco, below, foraged together in a mixed flock that included a spotted towhee and white-crowned sparrows.

An American pipit, above, travelled with eight other pipits through a grassland area. Large flocks of mountain bluebirds flew overhead. One group consisted of over 75 birds. At least 20 birds perched in the chokecherry shrub, below.

Ripe hawthorne berries attracted flocks of hungry American robins, including the banded bird above.

This week had the highest number of captures since banding started in mid-August. Species diversity decreased from last week as neotropical migrants continue to become less common. White-crowned sparrows, late season migrants, increased from the previous week. After weeks of consistent captures, no cedar waxwings were banded.

A rare Tennessee warbler (above) capture on the floodplain became the week’s highlight. This species breeds in the boreal forests of Canada and the northern US. The first captures of Townsend’s solitaire (below), another late season migrant, occurred this week.

Ruby-crowned kinglets dominated for a second week as they made another big push southward.

This week, RVRI banded 10 raptors of four different species. A male prairie falcon, the last of Montana’s four falcon species to be banded this year, provided the week’s highlight. With 56 total captures this season, RVRI is on pace to surpass fall 2012’s total of 63.

31 Raptor Trapping: September 29- October 4 This week, RVRI banded 10 raptors of four different species. A male prairie falcon, the last of Montana’s four falcon species to be banded this year, provided the week’s highlight. With 56 total captures this season, RVRI is on pace to surpass fall 2012’s total of 63. The crew captured one male prairie falcon this week (below). This is the first fall that RVRI captured an individual from all four of Montana’s falcons.

A prominent brow shades the eyes and provides the “serious look” of a young northern goshawk.

This week may be the largest raptor migration event in Montana history! A strong pacific cold front lingered in the northwest and northern Rockies for eleven days during the peak of migration. This storm dropped up to 20 inches of snow in the mountains and kept the ridges engulfed in clouds. Valleys to the north remained partly sunny, and the Bitterroot valley was the funnel. Every species, except the ferruginous hawk, was on the move. Small kettles, or groups, of mixed species were common as thermals developed. On October 1st, we counted a phenomenal 983 raptors, and 601 were turkey vultures. By the end of the week, the primary migrants were red-tailed hawks, broad-winged hawks, American kestrels, sharp-shinned and Cooper’s hawks. Rough-legged hawks made their first appearance of the season. The weekly total is higher than any season total we’ve had. I included the 2012 season total for comparison. Many factors combined for the perfect ‘migration storm’. The three other raptor migration sites in Montana report numbers that are well below average for this time of year. In fact, counts were abandoned due to the weather.

Merlin numbers doubled this fall.

This group of 23 turkey vultures found a thermal above our site.

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