Grouse digest pine needles and dance on dawn leks
Northern Hemisphere tetraonins—from arctic rock ptarmigan at eighty-three degrees north to Texas prairie-chickens—live on buds, leaves, and twigs that make up over ninety-five percent of adult diets. Forest species even thrive on conifer needles most vertebrates refuse, grinding them with grit and symbiotic caeca. Most males are polygamous showmen.
True grouse run thirty-one to one hundred fifteen centimetres and zero point three to six point five kilograms; add turkeys as basal tetraonins and wild males can hit one hundred thirty centimetres and ten kilograms. Feathered nostrils and, in ptarmigans, feathered legs and toes suit snow walking and burrowing. Spurs are usually absent except in turkeys and koklass. Hatchlings start on insects then shift to plants. Forest birds flock mainly in cold months; tundra willow grouse may gather hundreds, rarely a thousand, in winter. Rock and willow ptarmigan can migrate hundreds of kilometres—one Greenland-ringed bird turned up over a thousand kilometres south the next winter.
Courtship is theatre. Many species lek at dawn and dusk with coloured combs, inflatable neck sacs, drumming wings, and display flights; typical lekkers hold tiny territories and grow largest, exploded lekkers spread wider, and territorial resource-holders stay smaller—patterns that track sexual size dimorphism under sexual selection. Red grouse and willow ptarmigan are mostly monogamous; rock ptarmigan mix strategies, with polygamy rising toward the Arctic. Nests are ground scrapes; clutches of five to twelve pale spotted eggs incubate twenty-one to twenty-eight days, and chicks fly before two weeks old.
These birds bulk arctic vertebrate biomass and feed lynx, foxes, martens, and raptors when numbers boom. Prairie and forest forms have crashed with habitat loss; Gunnison grouse is endangered, greater and lesser prairie-chickens vulnerable, while managed red and ruffed grouse fare better. Hunters still take millions yearly, and folk dances from the Alps to the prairies mimic lekking cocks.
Source: Grouse
