Verification of Unusual Sight Record
For Utah

Rec. # 2004-29

Common name:

Broad-winged Hawk

Scientific name: Buteo platypterus
Date: September 26, 2004
Time: ~ 5 PM
Length of time observed: ~2 minutes
Number: 2
Age: Adult
Sex: ?
Location: Wellsville Hawkwatch. Located on the ridgeline about 4-5 miles due west of Mendon, Utah. The trailhead is at the end of 300 North (Mendon, UT) where a 3 mile hike will take you to the ridgeline and the official hawkwatch location.
County: Cache
Distance to bird: ~50m at closest
Optical equipment: 10x42 Leica
Weather: sunny with light southerly winds.
Light Conditions: sunny; during the best looks the birds were at 12 o’clock relative to the sun at 7 o’clock.
Detailed description of bird: On a beautiful late Sunday afternoon at the Wellsville Hawkwatch, the two volunteers watchers (Rob Spaul and Mark Fogg) and myself were kept busy with a steady stream of raptors, mostly Sharp-shinned Hawks and American Kestrels. Two buteos on the west side of the mountain caught our attention. The birds corkscrewed upward in relatively tight spirals using the thermals. At closest approach two birds were at eye-level about 50 meters due northwest from the hawkwatch station.

Both birds were identified immediately as smaller buteos based on their body size and relatively broad and medium length wings (jizz). The two most distinctive field marks that I observed were (1) the underside of the wings were relatively clean and white with a wide, distinctive black margin on the trailing edge of all secondaries and all primaries (remiges) and (2) the medium length tail was distinctive with its broad white tail band and terminal dark band. The belly was barred on both birds consistent with adults.

It was interesting that the two adult light-phased Broad-winged Hawks were closely associating with each other during their south-ward migration. They were not associating with other birds during the time that we observed them.

Both of the volunteer hawkwatchers concurred on the identification.
Song or call & method of delivery: not observed
Behavior: The birds were observed rising on thermals –a number of turns of the birds allowed close scrutiny from multiple perspectives. After reaching a height of about 50 meters above the top of the mountain they glided southward and finally out of sight
Habitat: High mountain ridge line running roughly north-south.
Similar species and how
were they eliminated:
Red-shouldered Hawk: Similar sized to Broad-winged Hawks but differ in (1) Red-shouldered Hawks have a distinctive light crescent near the terminus of the wing that is quite evident on both adults and juveniles. This is a feature that flags this species, especially on soaring birds. A crescent was not observed on these birds. (2) The tail band (white) were too wide for a Red-shouldered Hawk – the Red-shouldered do have bands of white and dark but they are much closer together and narrower. (3) Most Red-shouldered Hawks soar with their wings distinctively pushed forward. This was not observed. (4) Red-shouldered Hawks DO NOT show the dark band on the trailing wing remiges.

Swainson’s Hawk: The Swainson’s is more slender and pointed winged than the bird observed and DOES show dark remiges on trailing edge of wing however this species does NOT have a wide white tail band.
Previous experience with
this & similar species:
I have volunteered many, many hours at the Hamburg Hawkwatch in Hamburg, NY where I’ve been present when hundreds of this species have passed in one day. I’m quite confident of this species identification, especially in migration.
References consulted:  
Description from: Notes made later; From Memory
Observer: Jack Skalicky
Observer's address: 178 N. Main #55, Salt Lake City, Utah   84103-2075
Observer's e-mail address:
Other observers who independently identified this bird: the two volunteers counters at this site (Rob Spaul and Mark Fogg)
Date prepared: September 27, 2004 and e-mailed on October 1, 2004   (General Public)
Additional material:  
Additional comments: