10-06-15 Bird Field Note

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10-06-15 Bird Field Note

October 6, 2015

Kate Stone compiled this weeks bird field note. The note shows Northern Saw-whet Owl research, Curlew tracking, raptor trapping, songbird banding, a porcupine, and a flying squirrel.

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Bird Field Note compiled by Kate Stone 10/4/15 Northern Saw-

As of 10/4, we’ve captured 42 Northern Saw-whet Owls. We expect to finish trapping in the next week. Most of the owls we’ve captured are young of the year. In the past week, we saw a higher proportion of adult

Though the waxing and full moon made for beautiful evenings, we caught few owls on moonlit nights.

Compared to last year, we’ve seen more owls moving farther east and through higher elevations into the Sapphire Mountains. Few owls have used the Bitterroot Valley floor. The steep topography in the Sapphires limits detection range to as little as 0.25 miles; in the open conditions of the valley, we may detect a transmitter as far as five miles away.

One owl we followed into the Sapphires flew farther east than any owl we’ve tracked before. It flew 11.5 miles the night we captured it, stopped for one day at the Threemile Wildlife Management Area, and then headed east into steep hills above Ranch Creek, a tributary of Rock Creek.

A handful of owls have moved south along the west side of the valley. Several times, the owl shown below roosted at elevations > 6,000 ft. It also exhibited stopover behavior when it spent three days on the south slopes of St. Mary’s Peak west of Stevensville. For the past two days, it’s roosted on the slopes of Ward Mountain west of Hamilton.

As before, we observe a small fraction of the owls we’ve tracked to roost sites. Most of the time, we find them when they roost in shrubs and/or close to the ground.

We found a porcupine resting about 10 feet above a roosting owl.

Thanks to the effort of the Intermountain Bird Observatory, we continue to learn more about the migratory paths and overwintering areas of Long-billed Curlews breeding in the Intermountain West. “Dave”, the female from the MPG Ranch (in dark pink), breeds farther north than the other curlews in the study

Dave (dark pink) spent most of the past few months with curlews from Idaho (green and blue) and Wyoming (red) in agricultural fields southeast of the Salton Sea, near the Mexican border in California. As of 9/29, she had crossed the border and moved to agricultural fields southeast of Mexicali.

We recorded 650 migrating raptors this week, bringing our season total to 2,474. Turkey Vultures and Red-tailed Hawks dominated this week’s count, though Accipiters and American Kestrels also made sizeable contributions. The proportion of adult Accipiters increased. Because young Accipiters tend to move earlier than adults, this increase in adults may indicate that the Accipiter flight is tapering off.

We captured six raptors this week: four Sharp-shinned Hawks, one Prairie Falcon, and one Merlin. The Prairie Falcon was too small for a satellite transmitter.

We’ve deployed seven satellite transmitters on raptors this fall. Six of the birds are still moving south. The Prairie Falcon, which has held tight to an area south of Twin Falls, ID since September 14, may be on its wintering grounds.

During week six of fall migration banding, we captured 365 birds. Although our biggest days were at the Floodplain and Ridge sites (56 birds captured at each site), we caught more birds at Sheep Camp (131 captures). Classic fall weather conditions prevailed; we experienced near-freezing sunrise temperatures that warmed into the 70s by noon.

We captured a striking Williamson’s Sapsucker at the Ridge. Both sexes have a yellow belly wash, but only males display the bold black breast and upperparts, red throat, and white stripes by the mouth and eye.

The tiny Wilson’s Warbler weighs only about 7 grams. The large, glossy black cap indicates a male.

Different color crown stripes help us differentiate between adult and juvenile White-crowned Sparrows.

Northern Pygmy-owls are one of the tiniest owls in North America, but they are feisty and ferocious. This season, we’ve captured one Northern Pygmy-owl at Sheep Camp and four at the Ridge. This week we captured the banded breeding male from the nest near the Ridge. Our banding site is less than 0.25 miles from the nest tree.

full moon

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09-29-15 Bird Field Note