I have a pair of black swans and they have 2 babies (1 month old last Sunday). When I walk toward the pond, he is up at the fence hissing and hitting the fence, putting fed in the pen is a job, trying not to get swan whopped. I let him out this past week, and he almost killed everything on the pond and my cat also.
my mute swans were the same way when it was mating season and after the babies were born.
right now my mute swans will eat out of your hand.
so, it depends on what time of the year it is and if there are eggs or babies around to how nice they are
or at least that is the way mine are