My chicks are about 8 and a half weeks old and they still peep most of time, but when I pick them up, a couple of them make a sort of clucking noise. When it starts to get close to bedtime they start up with the most babyish sounding peeping (one of them is really loud!)and all try to climb up on my lap or hide under my legs. They are so cute. That always reminds me that although they are getting big, they are still babies. Then after I comfort them and put them up on the roost, they start to coo or purr to each other. I love when they do that, it's like they are having a conversation!