Some of our ducks (5 months old) seem to 'heave' as they breath, they aren't too tame so it is only a visual observation... Their chests and back sort of... well, heave, looks like they're about to poop or lay an egg or... but it just seems to be how it is with a good portion of them. One of the ducks who did it first and it seemed moreso than the others was off by herself in the pond one day (which seemed unusual). Then the next couple of days same thing, didn't come over when feeding the others! My partner was there when she died-- he swears he saw her slip and probably broke her neck, but I'm thinking something else must be up (maybe a respiratory issue made her more clumsy to fall?) and anyways not all of them do this-- yet! aNY thoughts, advise, etc.?