The last time I tried growing them was when I was a child. The built up excitement of fruiting ended in anticlimax as I found them all eaten one morning, before I had been able to pick them. My mother said slugs got them.
Now I wonder about that comment.
If snails took them you'd see strawberry "skins" still hanging there.
Edit: tip for removing snails without using questionable chemicals: pour beer into something that is easy for snails to enter. Leave out in the strawberry crop overnight. At least around here snails love beer and drink themselves to death.
That said, I grow a lot of these berries and for some reason the birds never go near em.
I think the strawberries aren't affected so much because they aren't a target for long, we pick them every other day through the season.