This pond ain't big enough for the both of us

Things are taking a rather nasty turn down at the pond. I noticed last week that the two parents were picking on one of the three cygnets, chasing them around the pond and today I discovered that there were only only two cygnets left. Presumably, it had been chased off or taken by the local fox. Today however, they were picking on one of the remaining two. In this picture, the parent was really going for the little 'un but was unable to catch him on account of swimming with only the one leg. However as titch sought sanctuary by getting out of the pond, "one-leg" managed to give him a nip and grab one of his tail-feathers. Perhaps this behaviour is supposed to make the cygnets try and fly, because as yet, I've not seen them attempt it.
The parents have also been sitting together a lot some way away from their remaining brood. It must be getting near mating time again.

Work is cak as usual.