Appearance and Behavior
The Svalbard rock ptarmigan (Lagopus muta hyperborea) is a subspecies of the rock ptarmigan (Lagopus muta) and the largest bird to stay on Svalbard throughout the year, including the dark winter months. While out hiking or skiing, this bird might be encountered, though it is often hard to spot due to its excellent camouflage. With a length of about 35 centimeters and a weight ranging from 490 to 1200 grams, depending on the season, the Svalbard rock ptarmigan can only be found in Svalbard and Franz Josef Land.
By the end of September, both males and females turn completely white blending in perfectly with the snowy landscape of the winter season. Males can be distinguished from females by a thick black line stretching from their beak to their eye, as well as by a fleshy red comb that appears above their eyes during the mating season. This red comb is much more pronounced in males than in females. While females change their plumage between April and May, males wait until July and August for their color shift. In summer, their feathers turn brown, providing them with camouflage against the rocky terrain.
Despite their ability to blend seamlessly into the environment, the Svalbard rock ptarmigan is not entirely silent. Males are known for their distinctive burping call, which often gives away their location, even when they are well camouflaged. These birds feed on various plants found in the tundra, and their feet are covered in feathers, giving them a snowshoe-like appearance to help them move through deep snow.
Life Cycle and Survival Challenges
The ptarmigan’s habitat changes with the seasons, but much is still unknown about their migratory routes. Males return to the same territory year after year, typically in late March, to prepare for the mating season. In contrast, females tend to select different territories and thus different males each year. The mating season is at the end of May, during which time males can have several females within their territory. The first female to mate with a male typically lays the highest number of eggs, with subsequent females laying fewer eggs and later in the season. The eggs are yellow-brown with brown-black speckles and blotches, and the chicks hatch after approximately three weeks of nesting, weighing only 16 grams. Within 10 to 12 days, the chicks are able to fly, and after 10 to 12 weeks, they will leave their mother to become independent.
The Svalbard rock ptarmigan’s population density is estimated to be around 1 to 3 males per square kilometer, but overall population numbers are unknown. They face predation from Arctic foxes, glaucous gulls, and Arctic skuas. Additionally, climate change is having an impact on the ptarmigan’s survival. The rising population of pink-footed geese, which compete with ptarmigans for the same habitat and key food plants, could significantly affect the ptarmigan population in the long term.
Léa Zinsli, PolarJournal