When I walked up the next morning the evidence was there. Something, and I suspect the red-tailed hawk that's been hanging around for a couple of weeks now, ate (I am guessing) a mourning dove, sitting on the path right near the shed. If I'd walked up when I noticed the exodus I might have seen it. On the other hand, I'd probably have chased the hawk off its meal, and life is tough enough for predators, especially this poor bird that is almost constantly harassed by the neighbourhood crows.
The size of the wing print is part of what makes me think that the diner was a red-tailed hawk.
The quantity and quality of the feathers is what makes me think this was probably a mourning dove. The mourning doves spend a lot of time sitting in the pines at the property line. They spook very easily, but this time the hawk was quicker.
Pity the poor mourning dove. Hooray for the hawk!