About the Svalbard rock ptarmigan

Description

The Svalbard rock ptarmigan (Lagopus muta hyperborea) is a sub-species of rock ptarmigan (Lagopus muta), which is a galliform bird of the family Tetranoidae. It is larger and heavier than both the rock ptarmigan and the willow ptarmigan on mainland Norway. The Svalbard rock ptarmigan shows large seasonal variations in body weight due to heavy fat deposition in autumn (500-550 g in summer and 900-1200 g in winter). More than 30% of the body weight in winter is fat. Both sexes have a white winter plumage except for black outer tail feathers.

Svalbard rock ptarmigan hen and cock

Svalbard rock ptarmigan hen (left) and cock (right) in June.Image: Kerstin Lye

The male (cock) has a black line from eye to beak, and in the breeding season also a large and fleshy red comb above the eye. Also the female (hen) has a red colour comb, but it is less visible.The hen changes into summer plumage in April-May. It is more red-brown than the Scandinavian rock ptarmigan and resembles the willow ptarmigan. The cock retains the white plumage until July and do not acquire the completely brown summer pelage similar to that of the female until mid-August. During September both sexes are again in winter plumage. The juvenile bird is more grey-brown than its parents and has a brown tail.

Diet

Purple SaxifragePurple Saxifrage.Image: Åshild Ø. Pedersen

The diet varies with season. Alpine bistort is the most important food source in summer and autumn. In late autumn and early winter various species of meadow-grasses and hair-grasses are important. From November-February purple saxifrage and tufted saxifrage are main food source, while polar willow increases in the diet from March-April and through spring.

Distribution

The rock ptarmigan species has a circumpolar distribution in the northern temperate and arctic regions, in addition to the Alps and the Pyrenees. The sub-species L. m. hyperborea is restricted to Svalbard and Frans Josef Land. The Svalbard rock ptarmigan is the only land-inhabiting bird, which resides in the archipelago throughout the year. It is a common nesting bird over most of the archipelago except for the most north-easterly parts. No breeding has been observed on Kvitøya, Kongs Karls Land, Hopen and Bjørnøya. The Svalbard rock ptarmigan use separate habitats during the winter- and breeding season. In many places it leaves the nesting areas in September-October. The location of the wintering areas and possible migration routes are unknown, but it is assumed that they seek to relatively snow-free areas such as under bird-cliffs and other areas with rich vegetation.

Breeding biology

Svalbard rock ptarmigan hen lying on nest incubating eggsSvalbard rock ptarmigan hen lying on nest incubating eggs.Image: Kerstin Lye

Ptarmigans get sexually mature during their first year of life (about 10 months). The cocks return to the breeding grounds in the middle of March where they establish a territory. The hens arrive in early April. The best habitats are located in south-facing slopes where the snow melts early. Cocks always claim the same territory in subsequent years, whereas hens change territory (and cock) but always come back to the same breeding grounds. Mating takes place in late May. The nest is placed in the upper part of the territory on dry ground and consists of a 1-2 cm depression in the ground lined with dead leaves. The egg laying occurs in early to mid June, but may be delayed in years with late snow melting. Repeated egg laying may occur if eggs are lost. Eggs usually number 9-11 and the successive clutches somewhat less. Cocks can have more than one hen in its territory, but the second hen lay clutches later than the first and produce fewer chicks. The eggs have a yellow-brown background with heavy brown-black speckles and blotches. The hen incubates for 21 days and the hatching weight of chicks is about 16 g. The hen and her brood leave the nest 1-2 days after hatching. They are fledged after 10-12 days, but remain with the mother for 10-12 weeks before becoming independent. The pair bonding disbands after the hen leaves the nest with the chicks, and the cock leaves the breeding site in mid-July in order to find better foraging grounds.

Conservation status

Svalbard rock ptarmigan cock showing territorial posturesSvalbard rock ptarmigan cock showing territorial posturesImage: Nicolas Lecomte

Norway has a particular responsibility in the management of the Svalbard rock ptarmigan, which is endemic to Svalbard. No population estimates exists for the whole Svalbard archipelago. After 10 years of monitoring in a restricted area (900 km2) the population of territorial cocks varies between 3-5 cocks per km2. The Svalbard rock ptarmigan is an important small game species, and the harvesting has been taken place without any information on population size and status. In 1997 reporting of hunting data started and hunting now requires a hunting license and since 1997 annual harvest has varied between 824 and 2500 ptarmigans. The Svalbard rock ptarmigan show less marked fear behaviour to disturbances during incubation compared to willow ptarmigan in mainland Norway. Despite that the Svalbard rock ptarmigan is regarded as extremely tame the high Arctic climate makes them vulnerable to disturbances during incubation.