I keep my chicks in my room, so I can hear every little peep that they make. Just now, one of them made a kind of whirring sound, almost like a cats pur. I have heard my older chickens make a similar noise on occasion, but one time I remember hearing it the most was when one of the older chickens was a few weeks old. My mom had it sitting on her knee and she was stroking its back. The chick suddenly stretched its neck into my mom's hand and rested its head on her wrist. Its wings drooped, its eyes closed, and it started making that whirring/purring sound every few minutes. I'm curious to know if anyone else has heard it and if they know why the chickens make that noise. Maybe when their happy?