for the last week this pair of mated mallard ducks have been flying in, staying a while and then leaving. As far as I know there is no fresh water pond near my house so I can't figure out where they are coming from. they seem to like the birdseed we are putting in the feeders. they came back again tonight for a brief period & then they flew off again. this is so odd. I wonder if they could belong to someone. they don't seem frightened by my husband and I & they look beautifully groomed. Any thoughts?