Rare Bird Report 9-B-09

IDAHO RARE BIRD REPORT FORM

Species reported: Gyrfalcon (Falco rusticolus)

Date and time of record: Oct 11, 2008; about 1pm

Reporter: Jay Carlisle

Idaho Bird Observatory, Boise State University, 1910 University Ave., Boise, ID 83725; jaycarlisle@boisestate.edu

Other observers: Heidi Ware (in trapping blind); Kyle Wright & Erin Burke were on hawkwatch (a few 100m away) and had the bird tentatively ID’d before the capture

Date report prepared: Jan 25, 2009

Locality: Lucky Peak (Boise Foothills), Ada Co. – hawk-trapping station

Habitat: open shrub-steppe on ridgeline – near deciduous shrub & conifer forest

Conditions: Cloudy, cold, and windy; some snow flurries during day and 4” of fresh snow from storm the night before

Did you takes notes? No.

Did you consult a field guide or other reference work? If so, which guide(s)? After observation: National Geographic and the Sibley Guide

Description of bird: A large, grayish raptor with long, pointed wings; a relatively long tail; and a strongly-hooked bill. The underside of primaries and secondaries were silvery in comparison with dark underwing coverts. The bird did not show a strong facial pattern. The bird had a wing chord of 400mm and weighed over 1600 grams.

Behavior of bird: the bird came into the hawk-trapping station in response to the flapping of the “lure-bird” (a captive Ringed Turtle-dove) and made many passes through the station before finally getting caught in a trap established around the dove.

How and when did you positively identify the bird, and what clinched the identification for you? The bird was first seen by Heidi and myself at about 50 meters distance and was flying directly towards the “lure-bird” (and us) in flapping flight. Head-on, my first impression was of a Northern Goshawk solely based on the grayish color and size (and because this species is much more expected at our site). When the bird arrived over the “lure-bird” and banked, I could see by the wing shape (long & pointed) that it was not an Accipiter but a large falcon. I then quickly noted size (slightly larger than a Red-tailed Hawk), color (gray), lack of strong facial pattern, and lack of any contrast in the axillaries and realized that I was looking at a Gyrfalcon!

List similar species and how you eliminated them: similar species include Northern Goshawk, Peregrine Falcon, and Prairie Falcon. Northern Goshawk can be similar in color and size but has more rounded wings – among other features. Prairie Falcon is smaller and more brown than gray and always has contrastingly dark axillaries (armpits). Peregrine Falcon is smaller and normally has a more prominent facial pattern. Also, Gyrfalcons tend to have an underwing pattern showing darker underwing coverts and a somewhat silvery underside of the actual flight feathers (more uniform in Peregrines).

What is your experience with this or similar species? Prior to this bird, I had seen 5 or 6 Gyrfalcons in South Dakota and one in Idaho – all either immatures or adults of the gray phase (or morph). I have seen hundreds of Prairie and Peregrine falcons as well as Northern Goshawks.

Describe your general birding experience: I have been birding for about 15 years.

Were photos, video, and/or audio obtained? Yes, see attached.

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