Female red grouse, a game bird found in Scottish moorlands; the plural of 'greyhen.'
English compound from 'grey' (describing the bird's coloring) plus 'hen' (female bird), used in hunting contexts since at least the 17th century in Scotland and Northern England.
Greyhens are the females of red grouse, which turn grayish in winter—hunters have used this term for centuries to distinguish them from males ('cocks') because the sex determines hunting regulations!
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