Rock Ptarmigan

Fascinating facts about the Rock Ptarmigan

• The rock ptarmigan is 34–36 cm long with an 8 cm tail, a wingspan of 54–60 cm, and weighs 440–640 g.
• In winter its plumage turns completely white except for black outer tail feathers and an eye line; in spring and summer the feathers become grey and brown.
• A bird ringed on Disko Island off Greenland was later recovered over 1,000 km (620 mi) south in Qaqortoq, and others have crossed the 300 km (190 mi) wide Denmark Strait to Iceland.
• The Svalbard subspecies can store up to 100 g (3.5 oz) of fat, enough to fuel ten days of starvation, whereas most rock ptarmigans carry no more than 20 g (0.71 oz) and survive only two days without food. This ten-fold difference in energy reserves reveals how a single population can evolve a distinct survival strategy for the harshest Arctic winters.
• Males display a bright red eye comb that grows larger with higher testosterone, and studies at Scarpa Lake, Nunavut, showed that first-year birds with bigger combs secured more mates, while older males relied on comb condition instead. The link between a tiny facial feature and reproductive success underscores how even subtle traits can drive the dance of sexual selection.

At a glance

About the Rock Ptarmigan

The rock ptarmigan (Lagopus muta) is a medium-sized grouse, 34–36 cm long with an 8 cm tail and a 54–60 cm wingspan, weighing 440–640 g. Its plumage is a masterclass in seasonal camouflage: winter birds are cloaked in pristine white, broken only by black outer tail feathers and a thin eye line, while spring and summer individuals don mottled greys, browns and subtle reds on the upperparts, with white wings and underparts in breeding males. A slender bill and black lores on males set it apart from the similar willow ptarmigan, and its high-altitude, barren mountain habitats, from the Arctic Cordillera to the Japanese Alps, reinforce its stark, rock-studded appearance. In the wild, rock ptarmigans are largely sedentary, yet the most northerly populations, such as those on Svalbard and Franz Josef Land, undertake impressive long-distance movements, crossing the 300 km Denmark Strait and traveling over 1,000 km between breeding and wintering sites. Their diet shifts with the seasons: in Alaska they nibble aspen, dwarf birch and willow buds in winter, switch to crowberries and lingonberries in spring, and feast on willow leaves, Dryas flowers and insects during the brief Arctic summer. A surprising trait is their limited fat storage, most individuals carry only about 20 g of adipose tissue year-round, enough for just two days without food, except the Svalbard subspecies, which can amass 100 g of fat, extending survival to ten days. This lean physiology forces frequent foraging even in the harshest winters, making the rock ptarmigan a relentless, adaptable forager of the high-latitude tundra.

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