Lighting is tough on this one, Bob - warm afternoon light from behind and cold blue light from the near side. A neutralised version is probably a starting point. The back light works really well on the cygnets. Fill flash would have been an option at capture. Some dodging on the head and neck of the adult may be useful.
Tony got rid of the color cast which is what I would have suggested. It would have been good not to have that one chicks body touching the adults head. Nice interaction your caught.
Robert and Tony covered the main technical issues. I did just want to add, that the far left cygnet is very cute, looking up at the parent. Title fits this little guy well!
It is always a challenge with mulitple subjects to get all of them with good head angles. If you could have moved a bit to your right, and lower, that would have taken care of the merge of the one cygnet and parent, and improved the head angle on the adult a bit.