This is one of at least 3 Thayer's we had today. We had a dark bird like this come overhead this morning, and keep going out of sight towards the Mississippi River. Shortly later we found this bird (sleeping in a different field at the time, looked to be the same bird), and we also had a much paler Thayer's, near Iceland in tone. However, the light bird still had the darker, uniform tertials and primary pattern shown by this bird.