IBRC 61-B-09

Idaho Bird Records Committee Rarities Report Form

Species: Broad-winged Hawk

Reporter:
Cliff Weisse
4125 Beaver Springs Rd.
Island Park, ID 83429
cliffandlisa@octobersetters.com

Other Observers: Lisa Weisse, contact info as above

Date of Observation: 24 April 2009

Date Report Prepared: 30 April 2009

Locality of Observation: Ashton, Fremont County

Habitat: The bird was soaring high over farms at the upper end of the Snake River plain

Conditions:  Sunny with light wind, sun high and behind observers at approximately 5:30 PM.  A snow squall passed through the immediate area about 1.5 hours earlier.  Duration of observation about 15 minutes total with a short drive between two locations.  Range was very long, too long to accurately estimate but color recognition was poor as a result.  I could easily see the light/dark pattern of the Swainson's Hawks when they banked but I had trouble with the pattern on the wings of the Red-taileds but I could see the belly band on one of the Red-taileds during turns that exposed the body to view.  We used Nikon 10x binocs only, no scope.

Did you take notes… No

Did you consult a field guide or other reference work?  Yes, later the same day .  The Sibley Guide to Birds, North Amereican edition

Description: This is a transcript of an email I posted on IBLE the day of the sighting:

"This afternoon we were driving dirt roads east of Ashton after a snow
squall passed through and we stopped to look at a kettle of four hawks.
Two were Red-taileds and I was just noticing that one was smaller (the
male of the pair) when a very small buteo strafed one of the
Red-taileds. It was obviously a buteo but looked about 2/3 the size of
the Red-taileds. We didn't get very satisfactory looks due to distance
but it appeared more compact than the Red-taileds, looked short-tailed,
the body was light below with no obvious dark markings, I didn't see any
obvious dark markings on the under side of the wings, and the wings
didn't have as much of a secondary bulge as the Red-taileds. At one
point when it was in a full soar Lisa pointed out that it held its wings
more forward than the Red-taileds. Although we couldn't get much detail
of the bird's plumage because of the distance and lighting conditions I
think we would have been able to make out the black and white tail if it
had been an adult so it had to be a juvenile."

The size difference between this individual and two each Red-tailed and Swainson's was obvious and remained obvious throughout the observation, it never lookd even close to as large as either RT or Swainson's Hawks in close proximity.  It was easy to see the size difference between the male and female Red-tailed in the pair and this bird was much smaller.  The tail looked quite short, although I believe that is an illusion.  Otherwise the bird appered similar to the Red-taileds structurally in direct comparison.  Although I couldn't be certain of the pattern on the under side of the wings they appeared essentially unmarked below.  I feel confident that the pale crescent of Red-shouldered would have been obvious, even at long range based on the appearance of the Swainson's.  Although the wings didn't have as much of a secondary bulge as the RTHAs there was a definite expansion of width in the secondaries.  This individual also held its wings further forward than the RTHAs, ie they angled slightly forward, or ahead, of the bird in a soar rather than being straight out like the RTHAs.   The underside of the body was seen fairly well several times and it was pale from tail to throat with no hint of a belly band, which was obvious on one RTHA I checked specifically to see if I could see the belly band.  It didn't appear rufous/rusty but color discrimination was not good.  

Behavior: I was looking at a pair of Red-tailed Hawks when this individual entered my field of view and harassed one of the Red-taileds.  It made several other passes at this pair of Red-taileds and once made a short dive between a pair of Red-tailds and a pair of Swainson's that were soaring in the same thermal, passing quite close to both species.  Other than the short dives towards the other buteos in the kettle it mostly soared with occasional bouts of flapping.  

How and when did you positively identify the bird, and what clinched the identification for you?  I felt confident that it was a Broad-winged immediately based on smaller size than RTHA and obvious buteo shape with apparent short tail.  When Lisa pointed out the wings held forward I became more confident of the ID.  I had no field guides with me so I checked Sibley when I got home, about two hours after the observation.  That's when I finally became positive of the ID.

How did you eliminate similar species, and what were they?  Small size compared to the RTHAs and SWHAs eliminates those species as well as the other regularly occurring buteos in Idaho, Rough-legged and Ferruginous, both of which were also seen on this day.  Swainson's, Red-tailed and Rough-legged are further eliminated by the pale underside as all three have distinct darker areas below, the head on Swainson's and the belly band on the other two.  Ferruginous is pale below but is much larger, obviously larger than Red-tailed in direct comparison.  Red-shouldered is small but it has a longer tail, narrower and more straight cut wings, fairly heavily streaked underparts in juvenile plumage (reddish underparts as adults), and obvious pale crescents across the primaries.  

Experience with this species: I've seen a few Broad-wingeds in Idaho and have seen them several times on trips to NJ.  I see hundreds of Red-taileds, Swainson's, and Rough-leggeds annually in Idaho and I'm very comfortable with identification of both those species.  I see a few Ferruginous Hawks annually.  I have less experience with Red-shouldered but have seen four in Idaho and several on trips to NJ and CA.

General experience birding: 17 years

Were photo(s), video, and/or audio obtained by you?  No