I've got 15 RIR's, all girls (nobody's crowed yet at 15 weeks). Just stepped outside for a quick check, and when I got to the coop, a couple of them were "purring"....almost singing. I play classical radio for them 24/7 and turn the light off at 10PM (til 7AM and then off at 9AM and back on at 8PM). Could they be trying to mimic the music? They go to layer feed tomorrow.