Wow, you are very fortunate to have such powerful ducks. I have had a coon get into my pen and eat two baby ducklings that were in a different section of the pen and not touch the big ducks but I don't think it was because my ducks were so strong. I think they were just lucky. It easily could have gotten to my others but decided not to. They claim most coons will go only after the duck food but my Son lost her whole flock of ducks and chickens to coons years ago. I have also had kids on my route tell me that they have seen a coon with two chickens, one in each hand strangling them. They caught it on their game cameras. They are usually vicious and a duck or chicken is usually no match for them.