Naked butt in three week old chick

[Needmorechickens]

I have 23 week old chicks I bought at Rural King. They are pretty much identical, although one has a naked bum and the other has a fluffy bum. Both act perfectly fine, there is no pasty butt. It just is naked. The first photo is the naked bum. The second photo is that chicks sibling. Don't know yet if their male or female. And the third picture is just a picture of the chicks themselves.

 

[Needmorechickens]

That should have said... three week old chicks, not 23 week old

 

[rosemarythyme]

I don't really see anything problematic. Different chicks feather in at different rates and sometimes they look rather ratty as they lose down in patches faster than they feather in.

 

[Needmorechickens]

Thank you, both of them had fluffy bums up until a few days ago. Then this one lost all of its fluff, maybe it is a Rooster? Or maybe it just hasn't grown feathers, he or she acts perfectly fine just like her sibling so I will watch it and see. They have been in a Brooder, but I have moved them outside for several hours for the last few days so I was wondering about fleas or Mites, although I don't see any.