First Alpine habitat group

Sul Ross's biology professor, Sean Graham, has taken groups to CMO before but this is the first time he brought one to our town ponds. I'm curious if they actually saw many birds.

Shortly before they arrived, my husband saw a raptor fly over but by the time I got outside it was far in the distance. Not sure what it was. At first he thought a Turkey Vulture. When I suggested it was awfully early for a vulture, that maybe it was a Golden Eagle, he decided it was an eagle. It flew in a dihedral manner. I never saw it close up like he did. When I showed Hugh photos of both species he was sure it was an eagle. He claims he saw white on the center of the wings. (He said that before I suggested an eagle.) I was way too far away to get anything but a tiny silhouette. What do you think? 

UPDATE: Kelly Bryan said the raptor is a Turkey Vulture. YAY! Spring has to be imminent!