Day 9 My heart sank!

My heart sank as I went out to take today's picture...they are gone!! Jim mowed the grass yesterday and came in and said.."Well you did it! They moved them.." I thought he was blowing smoke because in all my 56 years I have never known birds to move their young. I mean I can't even imagine how they could do it. Has anyone ever heard of that before? There is NO sign of stress, the nest is not torn up at all, there are no body parts left on the ground where an animal may have taken them.. The thing is ...Mom and Dad are still out there !
Now I am left with questions ...did an animal take them as I feared would happen or did the parents move them? If they have lost their little lives is it my fault because I should have left them alone? I mean I touched nothing! Didn't really get close enough to even breathe on them. I hate the unknown! They were just to young to fly away and something has happened to them, will I ever know what that was?