Feather detailing in Photoshop.

[Buttersauce]

This is Altaria fanart piece. You must look.
http://www.deviantart.com/deviation/30175035/

Yeah, I intend to colour this picture, but I really want to add, "realistic" details to it via Photoshop. What I'm asking is how do I go about doing this? See, I have been paying close attention to the varying details of parrot feathers (considering Altaria reminds me of most pet parrot species specifically the budgerigar). Even though I've did my homework, I'm still kinda stumped.

So, would it be like adding fur or is this a completely different matter entirely?