09-23-15 Bird Field Note

09-23-15 Bird Field Note

September 23, 2015

Debbie Leick compiled this weeks bird field note. The note highlights raptor migration, songbird banding, and owl banding.

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Bird Field Note Raptor Migration, Songbird Banding and Owl Trapping 9/20/15 Compiled By: Debbie Leick

We recorded 451 migrating raptors this week which brings our season total to 854. Accipiters, Red-tailed Hawks, and American Kestrels continue to dominate the counts. Our count of 14 Peregrine Falcons is a weekly record, and we are only two sightings short of a season record. In the past we have seen peak Turkey Vulture counts in the second half of September; we expect their numbers to increase next week.

We captured this season’s first Peregrine Falcon, Sharp-shinned Hawk, American Kestrel, Northern Harrier and Swainson’s Hawk. We outfitted a Cooper’s Hawk, a Peregrine Falcon, and a Red-tailed Hawk with satellite transmitters. The young Red-tailed Hawk below was too small to receive a satellite transmitter. The weight of the transmitter, harness and band must be less than 3% of an individual’s body mass to deploy a tracking unit.

This season we have outfitted many additional raptors with satellite transmitters (recent locations on map below). We outfitted one Prairie Falcon that is currently near Twin Falls, Idaho (white); a Cooper’s Hawk now in the Madison Range of southwestern Montana (orange); a Peregrine Falcon who has stayed near the ranch since we captured it on September 11 (purple), we’ve seen it at our lower count site on Indian Ridge; and a Redtailed Hawk whose last known location was near Hamilton, Montana (yellow).

We also continue to monitor previously outfitted Osprey. Helen (red), from the Sapphire Ranch nest, is the only adult Osprey from our study who has migrated. She left the Bitterroot Valley on September 2, and traveled over 1,500 miles to her wintering grounds in Mexico in just ten days. All three of the young Osprey born at the North Center Pivot nest this summer have begun their first journeys south. The first to leave (green) arrived at the McPhee Reservoir, near Dolores, Colorado, on September 8, where it spent the past week. The second young Osprey (yellow) has travelled around 1,000 miles since September 10, and is currently in the northeastern corner of New Mexico. The last of the young to move (blue) started September 15, and is still in the Bitterroot Valley.

During the fourth week of fall migration banding, we captured a total of 400 birds of 38 species. The Floodplain continued to be the most productive site, with 157 captures. We captured two new species for the project: Fox Sparrow and Mountain Bluebird (below). We experienced typical fall weather conditions; brisk mornings warmed into sunny afternoons with mostly clear skies.

This Fox Sparrow is a new species for our project, and for the MPG Ranch. We first captured it at the Floodplain site, then recaptured it the next day at Sheep Camp.

White-throated Sparrows have distinctive facial markings; the yellow lores, black crown stripes, and namesake white throat distinguish it from other species.

We captured two different subspecies of Yellow-rumped Warbler in the same net at the Floodplain site. Several facial characteristics helped us distinguish between them, including the presence of a supercilium or eyestripe (*) in the Myrtle Warbler, and differences in the definition and coloration of the auricular region (*).

In three nights of trapping, we’ve captured and deployed radio transmitters on 16 Northern Saw-whet Owls. We will track them as they migrate south through the Bitterroot Valley, and document their roost sites.

Owls blend in well with their surroundings. Low shrub roosts like this one are relatively easy for us to find.

We have a harder time locating owls in tall conifers. Some owls roost close to the tree trunk (below), but most roost out on the branches in clumps of needles.

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