Mmm, I think they'd be way too salty.
Are these jars or cans with a soon expiration date? I have read, and it has been my experience that food expiration dates are extremely conservative. Food is fine long after the expiration dates, for the most part. A visual and sniff test should bear that out. And pickled stuff with the high acid content and salt would be okay, seems to me.
For yourself, you need to make the decision and be comfortable with what you do, I am not trying to talk you into anything.
But I would not feed them to ducks because of the saltiness. Too much of a good thing.