Image A
Kentucky Ornithological Society
Swainson's Hawk (Buteo swainsoni)
8 April 2006
Sloughs Wildlife Management Area
Henderson County, Kentucky
Photos by David Roemer
An adult light-morph Swainson's Hawk was encountered near and over the Pond Creek Marsh on the Sauerheber Unit of the Sloughs WMA on 8 April 2006. First observed hunting/kiting to the east of the marsh, it was subsequently seen thermalling with an immature Bald Eagle over the marsh, rising with the thermal as they drifted downwind until out of sight. This represents the first confirmed record of the species for Kentucky.
A series of images was obtained as the birds thermalled high overhead. Equipment used was a Canon 20D/300mm 2.8 IS lens/1.4x teleconverter.
Two versions of each image are dislayed, the first being uncropped to depict what the bird would look like to the naked eye or through binoculars. The second, a cropped and enlarged version showing more closely the details of plumage and structure. The quality of the cropped images is expectedly poor due to enlargement but is sufficient to show the necessary features.
Two species which show similar contrast between white underparts and darker flight feathers must be eliminated, Osprey and light-morph Short-tailed Hawk.
Osprey may be heavily marked enough on the breast to approximate the appearance of a bib given less than ideal views, and Swainson's may lack a bib or be too distant for it to be visible. From below, Osprey exhibits a dark carpal patch and greater primary coverts which make the wing linings dark from the wrist to the primaries. The wing linings of light-morph Swainson's Hawk are pale to the base of the primaries. The bases of the outer primaries of Osprey are paler than those of Swainson's Hawk.
Osprey also soars with the distinctive bow in the wings, bent downward at the wrist, Swainson's Hawk with the wings held in a dihedral.
Light-morph Short-tailed Hawk is very similar to Swainson's, but lacks the bib and has paler bases to the outer primaries from below.
Light-morph Swainson's posess pale uppertail coverts which Short-tailed lacks, an important feature for separating the species when Swainson's lacks or has a split bib.
The first feature which alerted me to the bird being different was the combination of white unmarked underparts and brown (not rufous) tail. I've never seen a juvenile redtail with unmarked underparts, perhaps something to keep in mind.
Image A
Image B
Images A and B were obtained while the birds were overhead at the closest point to the observers. Even in the uncropped image, the strong contrast between the unmarked white underparts and dark flight feathers is evident. The dark bib and white throat can be seen in the cropped image.
Additional images of the Swainson's Hawk:
Swainson's Hawk - Images C and D ----------Swainson's Hawk - Images E - J