Hubby also took pics, so I went back and looked at those, and all of his shots show a straight leading edge to the wings. In real time, the bird was in full soar, as he was taking advantage of that thermal; there was little flapping or gliding. He seemed too large for a Sharpie, as we had the Red-tailed there for rough comparison and the white terminal bar was prominent, so I opted for Cooper's in the field.
Could @AlexHenryweigh in on this one?