10-02-14 Bird Field Note

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10-02-14 Bird Field Note

October 2, 2014

Kate Stone's Bird Field Note shows Saw-whet Owl tracking, a Brown Creeper caught for banding, and a Nothern Harrier Hawk.

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Bird Field Note Owl Banding, Shrubby Draws, Songbird Banding, Raptor Surveys Kate Stone 9/26/14 Owl

Northern Saw-whet Owl Tracking This week we began trapping Northern Saw-whet Owls. Our hope is to catch migrants, attach temporary radio transmitters to them, and then track them as they migrate south through the valley. In four nights of trapping we caught 18 owls and deployed transmitters on 16.

We use a UV light to help age the owls based on their molt patterns. Owls born this year show a uniform pink reflection under UV light.

This adult owl had an old eye injury and an apparent talon wound on its back. We banded it and released it without a transmitter.

Though we expected the owls to travel down the Bitterroot River corridor, several of them have moved along the base of the Sapphire Mountains. This owl travelled a minimum of 11 miles in one night, ending up in the Threemile Wildlife Management Area.

When possible, we track the owls on the ground to determine roosting habitat and substrate. Without a telemetry unit, we would not have seen this owl roosting just 2 inches off of the ground.

Over four days, this owl moved from the floodplain, up to one of the northern draws, then up to the slopes of Little Baldy, and then back down.

Shrubby Draw Surveys- September 18th Yellow-rumped Warblers continued to dominate shrubby draw surveys. We also detected many more Savannah Sparrows than we had in previous surveys.

We caught 431 birds this week, our busiest of the season so far. Our highest single-day total occurred on Monday, September 15th, when we caught 118 birds across all three sites. We also had our biggest day at any one site, capturing 50 birds at the Sheep Camp station on Wednesday, September 17th. Sheep Camp was the busiest site overall, with 193 captures over five days. We captured the fewest birds at the Ridge site. Our captures included a wide diversity of birds, from tiny kinglets and Common Yellowthroats to Sharp-shinned Hawks and an American Kestrel. Our top species included Ruby-crowned Kinglets (61) and Yellow-rumped Warblers (50).

The nets are designed to capture small- to medium-sized songbirds, but occasionally they trap small raptors. We caught this male American Kestrel in Sheep Camp on September 17th.

Young American Robins’ pale plumage distinguishes them from their adult counterparts.

We rarely catch Brown Creepers. They tend to stay close to tree trunks, where their plumage provides camouflage as they forage for small insects, spiders, and larvae. Brown Creepers build a hammock-shaped nest, often behind a loosened flap of bark on a dead or dying tree. They glue their nest together with sticky insect cocoons and spider egg cases.

Despite the unseasonably warm and sunny conditions, we have recorded over 1,200 migrants so far this season. Previous season totals by this date average only 500 birds. In the past week alone we had three >100-bird days (Sept. 9, 12, and 15). We continue to see high numbers of Turkey Vultures, Red-tailed Hawks, and American Kestrels. We expect kestrel numbers to decrease by the end of the month. Winter weather moves in next week, which may push raptors south.

The rounded tail and head projection of this juvenile Cooper’s Hawk distinguish it from the similar Sharp-shinned Hawk.

Northern Harriers’ long tails and white rump patch distinguish them from other raptor species.