Air under skin of chick

[Honora]

My mama hens and their chicks were attacked by a possum last night. One chick was killed and one of the hens has a small bite. Another chick was injured. He has no sign of a bite or a wound, but has a large lump on his right side near the shoulder. I think it's air under the skin.

Am I supposed to puncture this with a needle or will it get better on it's own? The chick is a week old.
(Don't worry, they will be locked up better tonight in case the possum comes back.)

 

[sourland]

Very likely an air sac has been injured/punctured. If the swelling is inconveniencing the chick, you can gently insert a hypodermic needle to reduce the swelling. If not just see if things resolve on their own.