Game animal populations and game management – time for change?

Climate change affects the numbers, diversity, and geographic ranges of game animals in Finland. Southern species are becoming more common, and the geographic ranges of species that have adapted to wintry conditions are narrowing. Climate change affects all levels of the food web and changes interrelationships between species, for example.

Significance of game management in Finland

The primary objective of game management is to maintain or improve the stock of game to be hunted and the balance between different species. A secondary objective is to shape game animal populations in order to increase their potential for use by humans. Methods include regulating game animal populations and maintaining and improving living conditions for game animals.

A total of 34 of the species of mammals and 26 of the species of birds found in Finland are classified as game. However, some of them are either wholly or partially protected by law. In 2008, the most important game animals included, among others, the mountain hare (Lepus timidus), the Mallard (Anas platyrhynchos), the raccoon dog (Nyctereutes procyonoides), the red fox (Vulpes vulpes), the European hare (Lepus europaeus), the Common Wood Pigeon (Columba palumbus), and the Black Grouse (Lyrurus tetrix). The game animal with the biggest commercial value in Finland is the Eurasian elk (Alces alces) [1].

Hunting is a popular pastime throughout the country, and the number of hunters in Finland currently stands at approximately 300,000 [2]. Hunting has both cultural and recreational value, and it encourages human settlement in rural areas and promotes the vitality of the countryside [3]. In the case of some species, hunting is also an important means of controlling populations.

Finnish hunters mostly hunt for private consumption, and game is rarely sold commercially [3]. The total notional amount of meat procured by means of hunting in 2008 was approximately 10 million kilograms, of which 7.5 million kilograms was elk. The value of game has increased in recent years, and the total value of game hunted in 2008 amounted to just over 70 million euros. A total of 52 million euros of this was attributable to different species of deer [1].

Climate change and the effect of weather conditions on game populations

Depending on the climate change scenario, average temperatures in Finland are estimated to increase by between approximately three and six decrees as a result of climate change by the end of the current century. Rainfall is also forecasted to increase, snow cover to decrease in Southern Finland, and the snowy season to become shorter throughout the country. Snowfall may increase temporarily in Northern Finland.

Weather conditions, such as temperature, humidity, windiness, and snow cover, are the most basic factors affecting the geographic ranges and abundance of different species of plants and animals [4]. Like other organisms, game animals have also adapted to living in certain kinds of local climatic conditions, and dramatic changes in temperatures and snow cover, for example, have an effect on the energy consumption of individual animals, on the availability of nutrition, reproduction, and the ability to shelter from disadvantageous weather conditions. The chicks of forest game birds, for example, are sensitive to changes in weather conditions, and they consume more energy and struggle to find food in wet and cold weather [3]. The predictability of the living environment is important for many species.

Because climatic tolerance is unique to each habitat type and species, different species react differently to changes in climatic conditions [3]. Climate change is estimated to affect at least the phenology, or annual rhythm, of plant and animal life cycles, the size and geographic distribution of populations, the composition of biological communities, and interrelationships between species [5]. For example, a longer growing season means better ecosystem productivity, and the increased availability of nutrition helps the young of animals to grow before the winter, allowing many species to expand their geographic ranges northwards. Climate change affects all levels of the food web. However, the upper levels are likely to be affected more heavily, which may damage food webs and cause major changes in biological communities [6].

Climate change may affect the population dynamics of small mammals and the geographic ranges of small carnivorous mammals

Climate change affects entire biological communities. Small game and small mammals in Fennoscandia are known for their cyclic population dynamics. Scientists have not been able to completely explain these changes in population size, but typically a cycle of several years of increasing vole populations, for example, is followed – after a slight delay – by an increase in the populations of the small carnivorous mammals that hunt them, such as the arctic fox. When the numbers of voles begin to drop, the shift in predation pressure is not immediate, and small carnivorous mammals continue to hunt voles, causing vole populations to decline further. Ultimately, the populations of small carnivorous mammals also begin to decrease or they begin to hunt alternative prey [3].

The population dynamics of small carnivorous mammals are less cyclic in the south than in the north, which may be due to lower snowfall, the abundance of omnivorous predators such as the fox, and the availability of alternative prey. If temperatures rise, the snow cover becomes thinner, or the snowy season shorter in Northern Finland as climate change progresses, many small carnivorous mammals may become more numerous further up north [3]. The active period of omnivorous predators that hibernate through the winter, such as the European badger (Meles meles), is expected to become longer with warmer spring temperatures, which may allow them to spread further north. On the other hand, the raccoon dog, for example, may not have enough nutrition available in snowy springs if temperatures rise but snowfall increases. Increasing snow cover may therefore restrict its dispersal to the northern parts of the country [7].

Increasing abundance of small carnivorous mammals in the north may increase predation pressure on small mammals. Together with decreasing snow cover, this is likely to stabilise the populations of small mammals in the north to some degree. This could have a positive effect on forest game birds, as it would decrease their importance as alternative prey for small carnivorous mammals [3]. On the other hand, the increasing abundance of the omnivorous red fox, for example, could also increase predation pressure on forest game birds. [8]

Effects on forest game birds are already evident

The populations of forest game birds have been decreasing over the last 40 years due to the fragmentation of forest habitats, for example. Climate change is also expected to have a negative effect on the numbers of game birds. The abundance of the European bilberry (Vaccinium myrtillus), which is an important source of nutrition for forest game birds, is estimated to decrease as species typically associated with coniferous forests dwindle. Changes in winter conditions and especially the hardening of the snowpack make it more difficult for forest game birds to survive over the winter. If the surface of the snowpack hardens due to repeated melt-freeze cycles, forest game birds will no longer be able to snow roost in order to escape from sub-zero temperatures and predators [3]. Southern Finland has experienced several almost completely snowless winters in recent years when snow roosting has not been possible. Harder snow also makes it more difficult for at least the Wood Grouse (Tetrao urogallus) to use subshrubs as a source of nutrition [9].

Decreasing snow cover also makes conditions less favourable to the Willow Grouse (Lagopus lagopus) and the Rock Ptarmigan (Lagopus muta), because their white winter camouflage is an adaptation to snowy conditions. The Rock Ptarmigan is found on treeless fell tops, which means that it needs to disperse to more northern areas as the tree line advances [10].

The Black Grouse has been observed to begin its courtship ritual earlier as early spring temperatures have risen, which has caused chicks to hatch earlier. Temperatures have not risen proportionally in early summer, however, which has meant that chicks have been born into cooler weather conditions than before. This has had a negative effect on the numbers of Black Grouse chicks [11]. The survival of chicks is also hindered by the shortage of insects, which are an important source of nutrition for chicks, in the cool conditions of early summer.

Forest game birds were previously known to exhibit cyclic population dynamics, but this has decreased or, in the case of some species, disappeared altogether in recent years. The cyclicity of game bird populations depends on several different factors such as weather conditions, predators, and parasites. There is some evidence that climate change is at least partially responsible for the longer cycles or the disappearance of cyclicity [11].

Southern species may become more numerous

Decreasing snow cover benefits many species that have dispersed to Finland from the south or been introduced by man, such as the European hare, the European rabbit (Oryctolagus cuniculus), the Common Pheasant (Phasianus colchicus), the Grey Partridge (Perdix perdix), the European roe deer (Capreolus capreolus), and the wild boar (Sus scrofa). The northern edge of the geographic ranges of these species is determined by the abundance of snow in the winter [3]. With decreasing snow cover, badgers are also likely to disperse to more northern areas. The European polecat (Mustela putorius), which is currently under threat of becoming extinct, may also benefit from milder winters [8]. As vegetation zones move northwards, species typical of European fauna are able to move with them. Species that have adapted to broadleaf forests are particularly likely to spread northwards.

Mild winters and unfrozen water bodies allow migratory birds to return to Finland earlier in the spring. More and more waterfowl are also able to winter in Finland, which eliminates the taxing migration process and allows the birds to begin mating earlier in the year. [3] An earlier onset of the spring melt means earlier nesting at least for the Common Goldeneye (Bucephala clangula) and the Mallard (Anas platyrhynchos) [12]. Not enough research has been done yet on the effects of earlier nesting on chick production. The reproductive success of the Common Eider (Somateria mollissima) depends more on the climatic conditions of the areas where the birds winter than on the climate of the regions where they reproduce [13].

Species that have adapted to wintry conditions may struggle

Climatic conditions and especially the volume and characteristics of snow and the length of the snowy season affect species that have evolved specifically to cope with snowy conditions.

Thinner ice cover and the earlier onset of the spring melt are disadvantageous to the critically endangered Saimaa ringed seal (Pusa hispida saimensis), the near threatened Baltic ringed seal (Pusa hispida botnica), and the grey seal (Halichoerus grypus). Ringed seals build their nests in snowdrifts on the ice and cannot reproduce without ice and a sufficient snowpack. The grey seal usually pups on pack ice but may also pup on land, although pup mortality on land is higher than on ice [3]. With thin ice, pups may die as pack ice breaks up.

Many species that have adapted to wintry conditions – such as the mountain hare, the Willow Grouse, and the stoat (Mustela erminea) – adopt white camouflage in the winter. The moult depends on the availability of light, which is constant even if the amount of snow decreases. White animals are not camouflaged in snowless terrain and are therefore vulnerable to predation [3]. With little or no snow, mountain hares are also more likely to be caught by foxes than when snow is deeper, because foxes cannot move in deep snow as well as mountain hares. [8]

Climate change affects competition between species

Wintry conditions also affect competition between species. Decreasing snow cover increases the competitive advantage of the European hare over the mountain hare. The European hare is larger than the mountain hare but less adapted to snowy conditions, because it lacks the white camouflage and large feet of the mountain hare that function as snowshoes. The European hare also has better access to nutrition in snowless conditions, because it prefers grass and clovers even in the winter (unlike the mountain hare that feeds on woody plants in the winter). With decreasing snow cover, the European hare can move across wider territories in the winter, spread northwards, and partially replace the mountain hare.

Competition over nutrition may also increase between the raccoon dog and the European badger, because they may remain active through milder winters. The availability of nutrition is at its lowest in the winter, which may increase competition. The raccoon dog may also compete over winter nutrition with other small carnivorous mammals [14].

supi © Esa Nikunen

The raccoon dog competes for the same sources of nutrition as the European badger, for example.

Conditions may become more favourable to deer at least in Southern Finland

The amount of snow restricts the movement and foraging of deer. If winters in Southern and Central Finland become less snowy, the European roe deer and the white-tailed deer (Odocoileus virginianus), for example, may become more numerous and spread to the northern parts of the country [3]. If snow cover increases in Northern Finland, deer may find it more difficult to move around and to dig for nutrition and become more vulnerable to predation. Elk in particular is likely to struggle in deeper snow and become more vulnerable to wolves. The Finnish forest reindeer (Rangifer tarandus fennicus) may actually benefit from increasing snow cover, because reindeer are more likely than elk to escape from the grey wolf (Canis lupus), and wolves may therefore begin to favour elk [15]. Frozen layers of snow make it more difficult for deer to dig for food from under the snowpack [12].

With thinner snow cover, elk are able to move around wider territories in the winter. This affects the relative prevalence of different species of trees and has implications on forestry, because damage to saplings may also spread more evenly across a wider area. If the number of elk increases in Southern Finland as a result of climate change, broadleaf trees such as the aspen (Populus tremula), the rowan (Sorbus aucuparia), and the pussy willow (Salix caprea) are less likely to reach maturity [3] and pine may lose ground to spruce [9]. The number of traffic accidents may also increase.

hirvi © Antti Below

An elk in a spring forest.

The populations of large carnivorous mammals depend on the availability of nutrition and hunting conditions

The effects of climate change on large carnivorous mammals are largely regulated by effects on their prey and other sources of nutrition [3]. For example, the increasing abundance of small species of deer in the northern parts of the country improves the availability of nutrition for the Eurasian lynx (Lynx lynx) [16]. The shorter winter season may affect the hibernation of the brown bear (Ursus arctos) [3].

The characteristics of snow cover, such as depth and hardness, affect the hunting success of predators in the winter. Soft snow makes hunting more difficult especially for the Eurasian lynx and the wolverine (Gulo gulo), because the lynx, for example, is not able to move as easily in deep snow as the mountain hare, which is one of its most important prey animals. Harder snow, on the other hand, benefits predators. Wolves may benefit from snowy winters, because elk are easier to hunt down in snowy conditions. The increased availability of deer carcasses after snowy winters may also improve the survival of wolf cubs.

Wolverine populations in Canada have been found to have declined the fastest in areas where snow cover has decreased the most over the years. Scientists believe that this phenomenon is due to wolverines finding it more difficult to hunt, to reproduce, to disperse to new areas, and to establish new territories, for example, as snow cover decreases. [17] Wolverines build their nests in snow dens, and they cannot reproduce without a sufficiently long period of snow cover. Snow dens protect wolverine cubs from predators and cold weather. Increasing nesting difficulties combined with the maximum summer temperatures tolerated by wolverines may push the southern edge of the geographic range of the wolverine further north and make the range narrower [18]. The wolverine is already critically endangered in Finland.

jäljet © Hanna Aho

Lynx tracks in soft dry snow.

Large carnivorous mammals may affect the ability of biological communities to adapt to climate change

Top predators may have a number of implications on entire biological communities in environments shaped by climate change. According to studies conducted in North America, the winter mortality of moose decreases with a warmer winter climate, which reduces the availability of nutrition for scavengers. Carcasses abandoned by wolves nevertheless improve conditions for scavengers and mitigate the effects of climate change on their populations. In North America, wolves are a stabilising force in biological communities [19]. In Finland, carcasses abandoned by wolves affect the availability of nutrition for wolverines, for example [17] [20].

Climate change may also affect the hunting success of predators and therefore the numbers of prey animals and other aspects of the food web, such as interrelationships between wolves, reindeer, and elk. According to studies conducted in the United States, the ability of wolves to hunt down moose improves during snowy winters. Within the studied area, this had a positive effect on the annual growth of balsam fir (Abies balsamea), which is the primary source of nutrition for moose [21]. The predators therefore helped to balance the food web. If the numbers of herbivores increase with increasingly favourable climatic conditions, the pressure from predators may control population growth and cause numbers to drop less dramatically after bad years [22]. Ambush predators that attack all ages of their prey species are particularly effective in balancing out variations in population size [22]. According to Norwegian scientists, the effect of the Eurasian lynx on roe deer populations may increase in areas where conditions are becoming increasingly snowy, and this may cause imbalance in the numbers of roe deer [23].

Care must nevertheless be exercised when applying these findings to Finnish conditions. For example, roe deer are a less important source of nutrition for lynx in Finland than in Norway, because lynx also feed on many other species [24]. Because conditions also vary in terms of snow, climate change can affect different parts of the country in different ways. The abundance and geographic distribution of populations of deer and large carnivorous mammals are also affected by human activity in Finland, and the impact of wolves on the abundance of elk, for example, is therefore local [25].

Diseases carried by game animals may become more common

Diseases and parasites carried by hares and rabbits, game birds, and waterfowl, for example, may become more common as a result of climate change. The increasing numbers and density of small carnivorous mammals such as foxes, raccoon dogs, and badgers may allow the parasites and diseases that they carry to spread more readily in Finland. For example, the role of the raccoon dog as a carrier or rabies and trichinosis in Finland has increased [3] [26]. Stronger communities of small carnivorous mammals may also allow the Echinococcus multilocularis tapeworm to spread to Finland from Central Europe, Estonia [27], or from the eastern coast of the White Sea. Humans are an incidental host of the tapeworm and can become infected with the parasite by consuming meat or mushrooms and berries that have been in contact with the faeces of small carnivorous mammals. The parasite causes liver damage in humans and may be fatal if left untreated. The introduction of the parasite to Finland could also affect berry picking and exportation to Central Europe [28].

Climate change, environmental implications, and the future of hunting

Any examination of the effects of climate change on game populations needs to take into account the fact that animal populations also face other major and simultaneous environmental changes caused by man, such as the loss and fragmentation of habitats. All environmental changes have distinctive effects, but together they can have major implications on many populations [29]. This combined effect needs to be taken into consideration when assessing the development of game populations. Changes in hunting quota and hunting seasons are likely to be required in order to mitigate the negative effects of major environmental changes on game.

References

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Authors