Lol. LOVE the vampire remark! Your friend is right about it not being a good idea to let your dog continue to kill marmots, but mainly just because it’s not nice to kill things, plus, it could be your neighbors cat next. However, Southern_pit is also correct. They are terriers. I had a jack russell/rat terrier cross and she was a better mouser than most cats I know! She also brought home a bird, squirrel, or rabbit from time to time. It’s the same thing as a golden retriever or a lab, that was bred to retrieve things, being awsome at playing fetch (which my pit doesn’t do.) There is no chance of your dog turning on you or any other human. You are viewed as a pack member, not food. Your dog is simply bringing dinner back to his family. It’s not something to be encouraged, unless you hunt, but it’s also not something that is going to cause your dog to transform into a blood thirsty monster.