First time with chickens, what’s going on with his skin?

[Lesserevil]

Could be picking while they are roosting, but loss on the back between the wings often is due to mounting.

How many chicks do you have? Could be you have another cockerel in the mix. Hard to know.

Observation during roosting and while they are occupied will often reveal what's going on.

There is 8 chicks. Was supposed to be the only cockerel. They are all the same age of 7 weeks today. I’ll set up a trail cam in the run and coop for tonight. Thank you so much.