Probably wishful thinking.
On my porch west of Berthoud, last week 3 individuals riding thermals and moving south.
Only reason I noticed was they were all white under and the wings seemed a different shape and wing angle than the usual red tailed, and no red. Then I thought I heard a call that was more like a whistle. By the time I grabbed my bins I only got a few seconds before they moved out of view. Of course once I looked them up in a guide I realized I should have looked for the black band on the tail. Maybe I would have noticed if it was there without looking for it or it was a juv?