The rock ptarmigan (Lagopus muta) is a circumpolar herbivorous bird characteristic of Alpine and Arctic tundra regions. In Svalbard the endemic Svalbard rock ptarmigan (L. m. hyperborea) is the only overwintering herbivorous bird (Løvenskiold 1964). The ptarmigan uses different habitats during the winter- and breeding season. In spring and summer shift in habitat selection coincides with the reproduction period, and a habitat quality gradient with the best breeding areas found in the south facing hillsides with early thaw in the inner fjord zone to the poorer sites along the coastline was found in the Ny-Ålesund area. The wintering areas and the extent of true long-range migration of the Svalbard rock ptarmigan are not known, but the migratory behaviour of the species is anticipated to be linked to food resources (Unander and Steen 1985).
Ecology - Diet
Ptarmigan generally prefer food of high nutritional value i.e. easily digested food with high content of proximal nutritional compounds where nitrogen and phosphorus seem to be most important (Unander, et al. 1985; Weeden 1969).
ptrarmigan - CROP
The ptarmigan store food temporarily in the crop (a thin, fleshy sac attached to the gullet and located along the neck between the skin and muscle of the chest) prior to moving into the gizzard where grit (small stones) helps to grind up the food items.
The diet consist mainly of herbs (i.e. Saxifraga oppositifolia, S. cespitosa and Dryas octopetala), shrubs (Salix Polaris) and graminoids (Poa spp., Alopecurus alpinus and Luzula confusa) during the polar night season (November–February).
In March and April, when birds return to the breeding grounds, Salix polaris makes up more than 50% of the crop content, and the contribution to the diet from this plant increases steadily from autumn to spring likely more related to availability than nutrition.
Before egg-laying (June) Salix polaris is the most important component of the diet and before nesting 90 % of the hen diet can consist of this plant. Alpine bistort (Bistorta vivipara) is the most important food item in summer and autumn, likely due to the high crude protein content of the plant The alpine bistort bulbils is especially important for the chicks, and their diet almost solely consists these bulbils.