I have certainly had this happen with my Golden Retriever, Honey, many times. Unfortunately, the birds weren't so lucky because she mouthed them to death. One thing I did when I realized that she had this ability, was to remove anything from my backyard that might encourage the birds to hang out there, including the feeder and the bird bath. As much as I enjoyed sitting on my patio and watching the birds, I was setting them up by doing it. Don't know if you have any of that in your yard, but if you do, you might want to move it out.

Logan (Retriever Lover)