Hybridizing species along the rivers across the Great Plains
(from R. T. Peterson's Field Guide to the Birds)
"Yellow-shafted" (eastern) and "Red-shafted" (western) Northern
Flickers
Baltimore (eastern) and Bullock's (western) Orioles
Variation in coloration of hybrid orioles
Rose-breasted (eastern) and Black-headed (western) Grosbeaks
and Eastern (formerly Rufous-sided) and Spotted (western) Towhees
Eastern Towhees extend westward along rivers across the Great Plains
and meet Spotted Towhees at the edge of the Rocky Mountains
but almost never hybridize!
Indigo (eastern) and Lazuli (western) Buntings
Like the grosbeaks above, these buntings hybridize on the Great Plains
where mixed pairs produce fewer offspring than matched pairs
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