We just put some on this fall and they do not hurt them, nor do they prevent them from eating, drinking, etc. Chickens only have two nostrils so put them in the hole and they will stay. All we did was put them in a cup of hot water to soften them, hubby held them and I put them on with my bare hands. Wasn't anything to it and only one hen was offended, but she got over it when we put her down. They are really simple, just take your cup of hot water and peepers out there and try it. Hubby didn't even hold their heads, just their bodies to keep them from flapping.