I have had a pair of mute swans for 4 years now and everything has been fine. About 3 or 4 weeks ago my female kept disappearing from our pond, after we searched for a while I found her in one of our pastures just setting there. I took her back to the pond and all seemed fine. Since that time she has wondered off about every other day and never tries to get back to the pond, I have to go get her and bring her back. She sees fine but a little down on her weight. She seem to have no interest in being with the cob that she has been with several years, do you know what is going on here?