Does this look normal?

[Kathy Golla]

If any other birds look like her with the feathers stripped from its shaft, treat them. Usually it’s just one bird unless the whole flock is under stress. It’s usually brought on by stress.

 

[Wyorp Rock]

Would it be wise to treat the entire flock with this or only the bird that is in question?

How does the rest of the flock look?