we have a pair of swans on our lake, and they had little ones, one baby has survived. MOm or Dad, not sure which one, had a leg or foot injury, and has died on the lake, which is now partially frozen, the other parent and one child that survived, are still here, in the frozen lake, not totally frozen, why are they not leaving ? would it be that the other parent is dead on the edge of the lake?

thanks Nancy