Svalbard reindeer

Last updated 10 November 2023

Management of the Svalbard reindeer (Rangifer tarandus platyrhynchus), which is only found in Svalbard, is an all-Norwegian responsibility. It is monitored because it is a keystone species in the terrestrial ecosystem in Svalbard, is considered to be sensitive to climate change and is hunted in parts of central Spitsbergen. The working group for the Conservation of Arctic Flora and Fauna (CAFF) also prioritizes reindeer monitoring.

Status and trend

The Svalbard reindeer occurs in varying densities in most parts of Svalbard that are not covered by glaciers. New estimates of the total population of Svalbard reindeer were published in 2019 based on a comprehensive population count. The population is estimated to consist of around 22,000 animals. It consists of six distinct and two mixed sub-populations. The species is experiencing increasing isolation due to the reduced distribution of sea ice.High temperatures in October and little snow at the onset of the Arctic winter have resulted in higher body weight in the following year and thus increased reproduction.

Brøggerhalvøya

In 1978, 15 reindeer were re-introduced to the Brøggerhalvøya: Annual counts show that the Brøggerhalvøya population grew exponentially until the winter of 1993–94 (N = 360).

This lengthy period of growth was probably due to a great deal of high-quality food being available at the time of their release and in the ensuing period. Autumn/winther 1993 was unusually mild and rainy on Brøggerhalvøya, and in combination with cold this led to the formation of a thick layer of ice over large parts of the area. This resulted in a population collapse due to high mortality and because some reindeer left the area. In the following spring (April 1994), only 78 reindeer were found on the peninsula. Since then, the population has stabilised and varied between 85 and 205.

Reindalen

The reindeer monitoring in Reindalen (1979–) includes the valleys of Semmeldalen, Colesdalen and Fardalen, and several nearby, smaller valleys. It began in 1979 with the aim of obtaining reference data from a population that was little affected by people. The density of the population has varied a great deal during the monitoring period and the data show large annual variations in winter survival and the proportion of calves in summer.

Up to the mid-1990s, about 250–650 reindeer were recorded in the monitored area each year. Since then, there has been a marked increase in the numbers, and about 800 have been recorded each year between 2000-2013. Since then, there has been an increase.

There is a controlled, limited hunt in the area.

Adventdalen

The reindeer monitoring in Adventdalen (1979–) takes place in this valley and in branch valleys as far up as Passhytta. During the monitoring period, the population density has varied considerably and the data show large annual variations in winter survival and numbers of calves per female.

The time series shows that the population grew comparatively slowly from 1979 to 1995 compared with the strong increase since the end of the 1990s. Between 700 and 1700  individuals have been recorded since 2000. There is still large inter annual variations in the total number of reindeer, the number of carcasses and the number of calves recorded.

No hunting takes place in the area now.

Causal factors

The Svalbard reindeer lives in a natural environment where predation is virtually non-existent and only limited hunting takes place in Nordenskiöld Land. Combined with the absence of problems caused by insects, few parasites and probably little competition from other herbivorous species, this simplifies the opportunities for finding out which factors influence its population dynamics.

2 factors mainly determine the variation in the number of individuals from year to year:

1. Density-dependence (competition for food resources)
2. Variations in climate (e.g. precipitation in winter, especially rain, and summer temperature)

Density-dependence is the link between the number of animals per unit of area and aspects of the life history, such as rates of birth and death and age of sexual maturity. Changes in these parameters affect the growth rate of a population. If the growth rate in a given year depends upon the number of animals that year (or the previous year), there is said to be density-dependence in the population dynamics.

Studies in Adventdalen and Reindalen have clearly shown that increases in population size lead to lower production of calves and higher mortality in the populations. This density-dependence in the population dynamics gives a reduction in the population if this achieves a high density and a growth in the population when the density is low. The Brøggerhalvøya population, by comparison, shows only a slight tendency for density-dependence.

An increasing number of studies of the monitored populations have shown that variations in the climate largely shape the population dynamics of the Svalbard reindeer. The climate mainly influences the Svalbard reindeer by affecting the growth of plants in summer and the availability of food in winter. Studies of all the monitored populations have shown that ice-covered ground in winter is the most important factor helping to shape the population dynamics. Winters with a great deal of ice give a reduction in the population because the ice covers the vegetation so that the reindeer cannot gain access to sufficient food. This results in increased mortality and reduced calf production. Frequent and heavy rainfall in winter is the main cause of significant icing some years. High reindeer mortality one winter is generally succeeded by less mortality and fewer carcasses the next winter because the weakest individuals have died. Higher summer temperature increases the plant biomass and leads to a longer growing season, which has a positive effect on the population growth rate the following year. High temperatures in October and little snow at the onset of the Arctic winter have resulted in higher body weight in the following year and thus increased reproduction.

The population development in the areas monitored in Nordenskiöld Land has shown a tendency to rise even though the frequency of icing in winter has increased during the monitoring period.

The reason for the increase in these populations is probably to do with positive effects of warmer summers and a later start to winter. Rising summer temperatures have led to increased plant production and a longer growing season and animals in better condition at the onset of winter. More recently, it has also been reported that mild periods in winter are also of such significance that they can open up grazing areas and actually provide increased access to grazing at a time when nutrient competition is normally high.

The population development in Nordenskiöld Land contrasts with the development in the coastal population on Brøggerhalvøya. Here it appears that the negative winter effect (rain and/or a lot of snow) is stronger than the positive effect from warmer summers (increased plant biomass). During the monitoring period, the population has been falling for much of time, but now appears to have stabilised.

Consequences

Meteorological data from Svalbard show that the frequency of rainy weather in winter has increased over the past 30 years. New climate models predict that the temperature will continue to rise and there will be more precipitation in winter, which will lead to more frequent rainy weather resulting in ice on the ground. This is a trend that may lead to a decline in the populations. At the same time, a warmer climate will probably result in spring starting earlier and longer growth seasons. These changes have direct effects on the plant communities in the shape of more plant growth and changes in phenological development. Such changes may bring better growth conditions for the reindeer populations and probably buffer or counter the negative effect of rainy winters.

The effect on the Svalbard reindeer of changes in biomass and the length of the growing season has so far only been studied on a limited scale in Svalbard. A study from Ny-Ålesund has shown that some of the variation in the growth rate of the population is a response to variation in the plant growth and the grazing plants on offer. A very recent study, that includes the Adventdalen population, has shown that the growth rate was positively influenced by the summer temperature. The outcome of a warmer climate on the reindeer will be determined to a large extent by the degree to which increased plant growth and longer growing seasons will affect the fitness of the reindeer and thus counteract the negative effects of rainfall and icing in winter. So far, it seems that the net effect of climate change varies locally, which is reflected in the rising population trend in Adventdalen and Reindalen, for example.

The Svalbard reindeer impacts the tundra ecosystem through effects on several trophic levels. For instance, it modifies the composition and structure of the vegetation. The tundra in Svalbard presently has little lichen and is dominated by grasses and herbs, but in the absence of reindeer it would to a large degree be covered by thick lichen mats. On Brøggerhalvøya, for example, grazing conditions have changed on both the species and the community levels since reindeer were introduced in 1978. In the future, the effect of density is likely to become stronger because the competition for limited grazing will increase.

In winter, carcasses constitute a substantial and important part of the arctic fox diet and a positive connection has been found between the number of carcasses available and the reproduction and population size of the arctic fox. Because of these trophic interactions, the Svalbard reindeer probably has a significant indirect influence on several other species through competition for food and varying predation pressure on ground-nesting birds due to changes in the arctic fox population.

The reindeer eat the same food as several herbivorous birds, including the Svalbard ptarmigan, which occur in low densities, and the migratory geese, chiefly barnacle geese and pink-footed geese, which occur in large, growing populations. The pink-footed goose eats many of the same plant species as the Svalbard reindeer. It removes plants with their roots and surrounding moss and directly affects the composition and structure of the vegetation locally, which may in turn lead to increased competition for the food resources between the species. So far, this appears to be happening to a small extent.

Recent studies have shown that the impacts of the winter climate lead to synchronous declines in the populations of the most important herbivorous species and arctic foxes. The interactions between the herbivores in the tundra ecosystem in Svalbard have still been little studied.

Both Adventdalen and Reindalen experience considerable human traffic by both snowmobile and on foot. The populations have grown in the monitoring period and studies have shown that the reindeer have a good ability to adapt to human traffic. This does not mean that human traffic has no significance, since it is impossible to know how the population dynamics would have been without that traffic. However, it seems realistic to believe that the populations in these areas are still not particularly vulnerable to human traffic on the present scale.

About the monitoring

The Svalbard reindeer is an endemic species (existing only on Svalbard). It is the largest herbivore and a key species for the tundra ecosystem because it affects and changes the vegetation and the population dynamics of the top predator, the arctic fox.

Even though polar bears have sometimes been recorded killing reindeer, the Svalbard reindeer lives in an ecosystem practically without predation and with almost no hunting. Hence, changes in the population of Svalbard reindeer can be a signal of changes in other parts of the arctic ecosystem.

Research shows that variation in the number of animals per area (density) and climate variation are the most important factors regulating populations. These factors controls the different populations monitored in different ways.

Svalbard reindeer can also be a possible parameter for monitoring the effects of disturbance from human traffic. This would require studies designed for this purpose, and no such studies are planned. Population data from the current monitoring will, however, provide an important basis for such studies.

The monitoring of Svalbard reindeer has now been expanded in COAT through a separate monitoring module that also includes drivers (vegetation, snow, ice cover, etc.) and spatial responses of the reindeer as a result of climate change.