Thanks Konrad. Its a pretty dark picture. After searching for images on the internet, I think I'm inclined to think its a young starling. I read that both cowbirds and starlings walk instead of hop, so I'm thinking starling. There have been several adult starlings around, but never with this little one. Maybe I'll try to lighten the pic. I should have done that to start with.

peregrines have a larger "mask" on their faces and paler breasts, and shorter tails Cooper's hawk: http://animal.discovery.com/guides/wild-birds/gallery/coopers_hawk.jpg

I'm thinking maybe a blue-headed vireo? I know the picture is pretty dark. But the eye ring and eye line and 2 wing bars make me think it might be the blue-headed.

Its a duck, a green wing teal I believe. Birds have a number of predators, small and medium mammals, other birds, reptiles. Could be a hawk or owl, or a cat or fox or raccoon. Squirrels even will raid nests I believe.