I can't say who did it. I suspect raccoons. Batman, the feral cat, would also be a good candidate except that he is injured at the moment with a gimpy back leg and I can't see him climbing up to get them.
The exact same thing happened to another nest last spring in the mower shed. I was so hoping these guys would fare better. I put up not one, but two security lights, including those creepy blinking red ones on the outside of the shed. I probably should have put one inside the shed as well.
The mourning dove eggs are also gone.