Svalbard rock ptarmigan (Lagopus muta hyperborea)

Svalbard ptarmigan
Photo: Øystein Overrein / Norwegian Polar Institute

The Svalbard ptarmigan is the small-game species that is harvested most in Svalbard. Knowledge is lacking regarding the size and trend of the population, and annual variations in the population. This knowledge is essential to ensure that the population is sustainably managed. In view of the climate, vegetation and snow melting, it is assumed that the nesting density of Svalbard ptarmigan is highest in the valleys of central Spitsbergen. This is also where most of the hunting takes place.

What is being monitored?

Density of males in selected areas

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The density of cocks which are defending territories has varied between 1.21 and 4.92 cocks per km² during the monitoring period. The material has not been analysed for statistical trends.

Status and trend

The Svalbard ptarmigan occurs in low densities, and in spring, there are only 1–3 cocks per km2 before the breeding season begins. The population, moreover, varies very little from year to year, by only ± 1 cock per km2, and the data so far show no particular trend.

Elsewhere, ptarmigan have cyclic variations spanning 6–10 years. So far, no cyclicity in the density of the Svalbard ptarmigan has been found, but the time series is not long enough to draw firm conclusions.

The development of a habitat model for ptarmigan has given information on the distribution of suitable breeding habitats for Svalbard ptarmigan on the island of Spitsbergen. The properties of both the vegetation and the terrain are important for the suitability of an area as a breeding habitat. The best areas are found in relatively narrow zones a little way up on south- and west-facing hillsides where Dryas heath is common.

Good habitats for ptarmigan have proved to be very limited and only less than 3% of the land area was of good quality. Thus, the availability of suitable breeding habitats seems to be a limiting factor for the population of Svalbard ptarmigan.

A pilot project has shown that winter migration takes place at the end of September and the beginning of October, but its significance for the management of the hunting is not clear.

Causal factors

There are still not sufficiently long time series to detect trends in the monitoring data, but some principal finds are that Svalbard ptarmigan occur in low densities and suitable breeding habitats are very limited.

These factors alone make ptarmigan in Svalbard vulnerable and several circumstances may be decisive for their vulnerability. For example, these may be direct climatic effects linked with changes in the onset of the growing season for important grazing plants, competition with a strongly growing population of pink-footed geese, and more indirect effects via the availability of carcasses and predation by arctic foxes.

Consequences

The Svalbard ptarmigan may be vulnerable to changes in climate because it can lose out in the competition for important grazing plants with growing populations of geese. Ptarmigan may also be exposed to a mismatch between the phenological development of their grazing plant, alpine bistort, and the timing of the hatching of their chicks.

Predation pressure from the arctic fox depends on the development in the geese and reindeer populations. This is related to the climate. We have shown that the winter climate in Svalbard, with periods of mild weather in winter with precipitation as rain, synchronises the entire community of herbivores in Svalbard – ptarmigan, reindeer and sibling vole. Vegetation covered with ice results in higher mortality and poorer production of offspring, due to less food being available. The reduction in the populations of the three herbivores is perfectly synchronised and coincides with the rainy winters.

About the monitoring

The Svalbard ptarmigan is an endemic subspecies of the ptarmigan and the only herbivorous bird species overwintering in Svalbard.

Hunting is allowed, and extensive hunting has taken place with practically no knowledge of the stock size or its status in time or space. 500–2000 ptarmigans are shot every year in central and in northern parts of Spitsbergen.

Knowledge of the population size of the species and its variation and development in time and space is required to secure its long-term, sustainable management.

Ptarmigan cocks arrive in the breeding areas at the end of March. Territorial boundaries are established soon after arrival, mainly in April. The breeding population can be expressed as the number of territories occupied by a pair of ptarmigans or cocks without a hen.

The Svalbard ptarmigan is a low-density species (1–3 cocks per km2 before the breeding season) and varies little from one year to enother (± 1 cock per km2) . Data so far show no specific trend. Good breeding habitats are limited and habitat models have shown that < 3% of the land areas are of good quality. Access to suitable breeding habitats thus seems to be a limiting factor for the population of Svalbard ptarmigan.

Places and areas

The area is part of Nordenskiöld Land and Sabine Land and measures approximately 1000 km².

Relations to other monitoring

Monitoring programme
International environmental agreements
Voluntary international cooperation
Related monitoring