Both male and female ruffed grouse have a ruff of feathers. It is much more pronounced on the males however. The tail feather band is only somewhat reliable as a sex indicator. Following is an excerpt from the RGS website:
"Ruffed Grouse are one of 10 species of grouse native to North America and are one of the smaller birds in the group, ranging from 17 to 25 oz. Ruffed Grouse are somewhat larger than pigeons, living their entire lives in wooded areas. The males are usually slightly larger than the females, although an occasional adult female will exceed a young male in size. Backdrop14B-WEB2The name "Ruffed" was derived from the long, shiny, black or chocolate colored neck feathers that are most prominent on the male. When the cock is in full display in defense of his territory, or showing off to an interested hen, these feathers are extended into a spectacular ruff which, together with a fully fanned tail, makes him look twice his normal size.
The plumages of the two sexes are quite similar, and while about 77% of the males have unbroken dark bands near the end of their tails, many males have incomplete bands much like those of females in which the color is faded or absent on the central tail feathers. Out of a sample of nearly 1700 grouse, the same band patterns were common to both sexes among 52% of the population. The best external basis for determining sex is a measurement of tail length. Across most of its range, a fully grown tail feather over 5-7/8 in. in length usually belongs to a male; less than 5-1/2 in. to a hen - but birds with intermediate measurements can be either male or female. When this occurs, two other procedures are useful. One is to examine the feathers on the upper side of the bird's rump, just above the central tail feathers. If there are 2 or 3 whitish spots, the bird is probably a male; if none or one, a female. Another procedure is to compare the length of the 2nd primary flight feather from Sheets Grouse 4the wing tip to the length of the central tail feather. If these two feathers are about the same length, the bird is a hen; but if the tail feather is more than 3/8 in. longer than the wing feather, he's a male! For drawings and more details, please refer to the publication, A Grouse in the Hand and the YouTube video Determining Age and Sex of Ruffed Grouse."
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