Fox can also take geese, they have been seen here on golf courses taking out canadian geese and you don't need large dogs to take out a goose. A few years ago we had a french bulldog that was great with everything but birds, she hated birds. She snuck out the door and was only out a few minutes when I heard the noise and ran outside. In those 3 minutes, she killed 2 6 month old geese and seriously injured 2 others. One so bad I almost put it down and probably should have but it continued to eat and drink, so I gave it a chance and he recovered. She weighed 20 pounds and was 11 years old at the time, she just chased them down and jumped on their backs, grabbing them by the neck. At 6 months the birds were full grown, but still acted young, perhaps that didn't help as they all ran instead of fighting back, but I don't think it would have mattered.