Idaho Bird Records Committee Rarities Report Form

Rare Bird Composite Report #: 81-B-06

Species: Broad-winged Hawk

(composite report of 215 sightings between 1995-2006)

Reporter: Jay Carlisle

6105 Kirkwood Rd

Boise, ID 83709

jaycarlisle@boisestate.edu

Other Observers: multiple Idaho Bird Observatory hawk migration counters including myself, Ryan Brady, Craig Fosdick, Justin Barrett, Dusty Perkins, and Greg Kaltenecker

Date Report Prepared: 12-5-06

Date Sightings Occurred: 12 fall migration seasons spanning Sept 7, 1995 through October 3, 2006. Please see attached table showing the date/year of each sighting.

Locality of Observation: Lucky Peak, Boise Foothills, Ada Co.; an Idaho Bird Observatory migration study site

Habitat: north-south trending ridgeline with a patchy mosaic of shrubsteppe, mountain deciduous shrubland, and conifer forest

Conditions: Most Broad-winged Hawks have been seen during high pressure weather and light to moderate winds. Observers have been well-trained in in-flight raptor identification and have used 8x and 10x binoculars; occasionally a spotting scope (20-60 zoom) was used to confirm ID of distant birds. At least 2 observers were present during all observations.

Did you take notes? no

Did you consult a field guide or other reference work? Before, during, and after the observations. Observers used the following field guides to prepare for the season and to study up during the season.

What guide(s) or reference(s) did you consult?

‘Hawks in Flight’ by Dunne, Sibley, and Sutton; ‘A Field Guide to Hawks of North America’ by Clark; Sibley & National Geographic

Description: The major fieldmarks used to identify migrating Broad-winged Hawks were: relatively short wings; somewhat pointed wingtips (more so than in other Buteos); a less distinct (immatures) to distinct (adults) dark trailing edge on underwing; broad tail with alternating dark and light bands (2 shades of brown in immatures; black and white in adults), and smaller size in relation to Red-tailed Hawks (the common Buteo that migrates past the sight). The majority of birds have been immatures but adults are recorded in most, if not all, years (see pictures).

Behavior: All birds were seen as active migrants passing by the observation point at Lucky Peak (2 of which were captured). Most, if not all, Broad-winged Hawks were seen in a combination of flapping, soaring, and gliding flight. Fieldmarks are easiest to see when soaring but gliding birds are still appreciably smaller and with more pointy wings than Red-tailed Hawks.

A note on timing patterns (see attached table): While numbers have varied from year to year, there is a discernable pattern in which most Broad-wing sightings occur in mid-to-late September with less frequent sightings occurring in late August into early September and again in early October. This pattern fits timing for eastern hawk watch sites where this species is much more common. The Oct 25 sighting is outside the normal Lucky Peak pattern and is either a very late individual or a mis-identification (I was not present for this sighting but my sense is that a well-trained observer would have to be quite certain to record a Broad-wing at this date).

How and when did you positively identify the bird, and what clinched the identification for you? Each bird was identified by a combination of the features mentioned in the Description section above.

How did you eliminate similar species, and what were they? Possibilities include Red-tailed Hawk, Swainson’s Hawk and the rare Red-shouldered Hawk. Each of these species are larger (especially Red-tailed and Swainson’s) and Red-shouldered and Swainson’s Hawks have proportionately longer wings. Lighter morphs of Red-tailed Hawk show an obvious dark area on the patagial area of the underwings. Swainson’s Hawk wings are long and more tapered than in Red-tailed and lighter morphs tend to show a very broad dark trailing edge to the underwing. Lastly, Red-shouldered Hawks have more tail bands as well as a crescent-shaped light patch on the inner portions of the outer primaries.

Experience with this species (and similar species): Hawk counters at Lucky Peak see well over 500 Red-tails, between 25-100+ Swainson’s Hawks, and an average of just under 18 Broad-wings per year. I personally have observed many thousands of these three species all across the US (western/central US for Swainson’s) and in Latin America. There have been 8 sightings of Red-shouldered Hawk from the same site as well as one bird captured and banded at our Boise Peak banding site (see separate reports). I personally have seen well over 100 Red-shouldered Hawks in many US states (CT, CA, SD, ID, etc.) as well as in Mexico.

General birding experience: extensive; 14+ years in US and Latin America

Were photo(s), video, and/or audio obtained by you? (If yes, please include or attach) : Yes; see below for representative photos

HY dark Broad-winged -- 9/25/95

24 September 2003