I just gave some day old chicks to my broody hen. Initially she was scared and ran away to be with the other hens, so I shut her out and shut the babies in. After a while she seemed to want to go back inside and this time she accepted the babies. When she had pushed them under her, she did a strange thing with her tongue - she opened her mouth and vibrated her tongue up and down as if she was panting, for ages. It seemed to be almost an expression of joy. Does anybody know what this is?