My hens make a little noise when I come out to feed them treats. The rooster makes the same sound but it sounds deeper. To me this is the sound my rooster makes to call the girls when there's food around or just to call them to where he is. The sounds you hear may be normal "coming of age" sounds. I would monitor you flock for signs of illness like laying around not doing anything or not eating. If they are acting normal in every other way, I would just observe. When the birds make those noises, watch to see what they're doing and if they change what they're doing. It may be simple communication between birds.
Also, "cull" means to do away with. Give away, rehome or euthanize. I do not recommend this for your birds at this time. "Closing the flock" means killing your entire flock.
Also, "cull" means to do away with. Give away, rehome or euthanize. I do not recommend this for your birds at this time. "Closing the flock" means killing your entire flock.