Swainson's hawks can be found in many variations including this Dark Morph. According to an article by Bill Chaisson, these color variations are only found in 10% of the birds. This one seem particularly dark to me and I had to take a better look as there were light morph Swainson's hawks on every second pole and this one just seemed different. The white and black barring under the tail feathers gave the bird away but it was a bit of a search through some photos and the bird book to make sure. This was just north of Felt, Oklahoma