This is my biggest fear. My pup LOVES going outside to play, and loves rolling around in the grass, but I don't let her go out alone. She is easily small enough to carry off right now, but I expect her to top out at around 7 lbs.
My father lives about 10 minutes away in a neighborhood with lots of trees, and several of his neighbors have had small pets go missing. I'm sure they were taken by birds of prey. One year, there was a hawk nesting high in one of his trees, then the next year a horned owl took up residence in the nest and raised some babies there. There were always feathers and "parts" of victim birds scattered on the ground under the tree when the owl lived there.
One day we were looking up in the tree and could make out the outline of the owl against the bright sky, "horns" sticking up on either side of the owls head. Hubby said it looked like a Yorkie sitting way up there, LOL.