First, they could be irritated as their new feathers come in. Mine will often excessively groom as their "pinfeathers" (the new feathers in their casings) come in.
However, I would thoroughly check your babies for any other signs of lice or mites, including the bugs themselves. They're nearly microscopic, so check each of your babies very thoroughly - particularly under the feathers in warm moist spots. Look for any little white clusters of "stuff" which could be lice eggs.
To catch mites, you'll have to go to the coop at night and check then. Turn the coop light on, but then use a flashlight to see better as you check under their feathers. Also check in the cracks of the wood for mite eggs as that's where they lay their eggs when they're off the birds.
If you find either, treat the birds with a **permethrin** dust. Not pyrethrin or Sevin dust (carbaryl). You can find it at feedstores and
TSC stores labeled as "poultry dust" or "garden and poultry dust" or "livestock lice dust". Just read the active ingredient to make sure it's PERmethrin.
If you have lice, you can treat the birds, nest boxes, and bedding. If you have mites you treat all of the above but must also treat the wood, eyes in the wood, joints, and on the walls up to 3' high on the walls. For those applications, the 10% permethrin spray, Ectiban EC, or a permethrin goat lice spray is great to spray on the walls (while the chickens are outside). It's easier than making a paint out of mineral oil or water and the permethrin dust, though you can certainly do that too.
For bedding, scrape the bedding aside - dust the floor - replace bedding - dust the bedding, stir in well. For runs, dust on the ground, rake in. etc.
Also at that age they tend to pick at one another a lot. Make sure they all have plenty of space, get a good age-appropriate starter or actually a grower now, with a good protein level. I don't feed anything under 20% to my babies that age.
I hope this helps.
What breed are they?
