I have Indian runner ducks for training stockdogs. My friend had a flock used for the same purpose however her entire flock was killed (I was told raccoons) except for 1 Pekin duck aptly named Mrs. Pekin. Mrs. Pekin's 5 ducklings along with many other ducks died right in front of her. After the attack Mrs. Pekin sat for 3 days and wouldn't eat/drink/walk. After that she became mobile although very quiet. Two weeks after the attack (Thanksgiving day) I drove across the state and picked her up so she could overwinter with my flock. When I went to get her from her cage she was so scared she attacked me. Ditto when we arrived at my home and I got her out the travel crate. When she saw my flock of ducks the silent bird turned into a quacking excited whirlwind. She chased the flock of startled runners through the yard and it took a few hours until she calmed down. She spent the next 2 days eating nonstop between bouts of separating off and chasing the drakes quacking loudly and happily. (Note: she was not quarantined as some of my flock came from her flock originally, she was very stressed mentally, and she was inspected for lice etc. I do normally quarantine.)
Mrs. Pekin seems to have limited mobility (injury last spring?) and is rather slow. Because she is slow and because she panics at the sight of a dog she is put away before all herding lessons. My dogs and the runners ignore Mrs. Pekin's panic (dogs are outside playing fetch etc while ducks are running loose, supervised of course). Mrs. Pekin will actually abandon her flock, race madly to a hidey hole, and sit in the corner while quacking and shaking for long periods of time when she spots a dog etc. (the neighbor's dogs love to bark through my fence at the ducks- runners ignore it completely). Mrs. Pekin has always been a rather strange, loopy duck but her behavior is so extreme. She's been at my place for about 2 1/2 weeks now and has calmed down considerably. She does still chase the drakes daily which is kind of amusing to watch. Sometimes the hens are so annoyed by her chasing the drakes the hens then chase Mrs. Pekin. The drama. . . my quiet flock has turned into a soap opera. ;)
So, have other ducks suffered these extreme stresses and how long did it take for them to recover? I suspect Mrs. Pekin may need to go to a dog/cat-less family in the spring instead of back to my friend's farm when she restocks her duck flock. She was molting heavily and had stopped laying eggs when I went to pick her up. She's still molting but from the loud quacking 24/7 I think she's happier than she was and seems a bit calmer every day.