The male sage grouse has air sacs that, when not inflated, lie hidden beneath the grouse' s neck feathers  During its spring courtship ritual, the male sage grouse inflates these air sacs and displays them to the female sage grouse
Some scientists hypothesize that this courtship ritual serves as a means for female sage grouse to select healthy mates
When diseased male sage grouse were treated with antibiotics, they were not selected by female sage grouse during the courtship ritual.