...and, right on cue, the hawk appears:
Look carefully, that's a dove it's snacking on.
Tentative identification of the villain is a female Northern Harrier, a.k.a. Marsh Hawk, Circus cyaneus, but it was a long way away and refused to turn around for a mugshot. The evidence is, however, compelling enough to clear the original suspect, an immature Broad-winged hawk, who was around last winter. He is now out on bail for his other crimes (trespassing in Canada when supposed to be overwintering in Florida, with malice aforethought). The score is, nevertheless, Doves 0, Hawks 1.