Ruffed grouse are a type of forest grouse found in North America. The males and females of the species have distinct physical characteristics, with the males being larger and having a more elaborate ruff of feathers around their necks. The females are smaller and have a less pronounced ruff.
The different physical characteristics of the males and females of the species are thought to be due to sexual selection. The males’ elaborate ruffs are thought to be used to attract females and establish dominance over other males. The females’ smaller size and less pronounced ruffs are thought to be due to their need to be more agile and camouflaged in order to avoid predators and care for their young.