was about to say there can also be other reasons for a bird throwing 2 together and holding them back is one as the bird trys to bolt the wing to catch up to where nature tells it it should be its not allways a sign of good form it can just be natures body clock telling the bird it needs to catch up so to speak so having the bird on darkness for 6 weeks would cause it to try and and bolt the wing to catch up imo seen widowhood birds do the same when paired after racing