It wasn't me what ate your birds, but it could have been some of my pals.
Us cats do eat birds but I think that we are getting bad press. Cats and birds have been around since I was young (I am three this year) and they will continue to be around until I am old. I think that the culprit is a big scary bird.
I hope that your birds come back - I am an avid bird watcher because I live indoors and have never tried to attack any bird, but the pigeons on the roof are noisy and one day I might get out the Velux window and.........