The Effect of Global Warming on Arctic Wolverines - Research Paper Example

 Abstract While the northern latitudes at which wolverines live are vulnerable to the effects of the global warming, there is little sign as yet that climate change is having a significant impact on wolverine populations and behaviour. There appear to be ample habitats suitable for wolverines, and their population levels are certainly not being curtailed by the loss of habitats due to climate change. The main problem for all wolverine populations is the growth of human habitation and land use into areas they inhabit, and therefore the increase of conflicts between wolverine and human populations. It is human persecution of wolverines that has been the central factor in determining wolverine populations and distribution for centuries, and this continues to be the case. The effects of climate change on wolverine populations remain negligible. Problem Statement It is clear that over the course of the last two centuries, the total population of wolverines has undergone a dramatic decline. Furthermore, the geographical distribution of wolverine habitats has experienced a sharp retraction, with the general trend being the abandonment of what were previously the southernmost regions in which they lived. In the past, some writers have identified the North American wolverine (Gulo luscus) as a species distinct from its Eurasian counterpart (Gulo gulo). However, as Abramov et al. have noted, more recent authors have generally reached a consensus that the North American wolverine is just a sub-species of the Eurasian wolverine. Therefore, for the purposes of this study, the term ‘wolverine’ will be used to deal with both variants. The wolverine is the largest terrestrial member of the weasel family (Mustelidae). In appearance, the wolverine is sometimes likened to a bear, but its behavioural patterns and movement place it firmly with the weasel. They are generally scavengers, surviving on the remains left by other predators, and on animals killed by disease and accidents, as well as rodents. They also come into conflict with humans by killing sheep and reindeer, especially in Scandinavia. The wolverine is distributed in several regions surrounding the arctic, in the Boreal Zone. They are currently present in Scandinavia, European Russia, Siberia, Alaska, Canada and some of the mountainous regions of the western United States. Within these regions, the wolverine is versatile in terms of its habitat, and is found in tundra and alpine zones, and in deciduous, coniferous and mixed forests. However, the total area across which wolverines are distributed has undergone a significant retraction since the 19th century. In general terms, the southernmost regions in which wolverines were once found are no longer inhabited by them. Historically, as Landa et al. state, the habitats of wolverines in Europe were spread as far south as southern Sweden, Estonia, Lithuania, and north-east Poland, but they have since disappeared from these regions. The existence of laws protecting wolverines in several countries, including Norway, Sweden and Finland, is testament to their declining numbers since the 19th century. In western Canada, for example, they are listed as a Species of Special Concern, meaning that they are possibly becoming threatened or endangered, and they have been harvested for their fur in this region for 200 years (Lofroth and Ott, 2193). Wolverines now reside mostly in regions north of the latitude 60°N. Several factors have contributed to this change, among which must be numbered the gradual spread of human development, human habitation and other human land use, and consequent persecution by humans. It is the purpose of this study to determine whether climate change might also be counted among these factors, and to determine its relative importance. Research Question Have climate change and its associated processes had a verifiable impact on wolverine populations, and how significant are these factors in relation to the other factors currently affecting wolverine populations? Literature Review Much of the literature concerning the current state of wolverine populations worldwide is concerned primarily with methods of measuring the scale and distribution of those populations, so that viable management strategies can then be formulated. Examples include Sæther et al.’s study of wolverine populations in Scandinavia generally; Lofroth and Ott’s study of wolverine populations in British Columbia, Canada; and Magoun et al.’s study of wolverine populations in Northwest Ontario, Canada. In 2005, Magoun et al. surveyed some 60,000km² of Northwest Ontario from the air. Having split this vast area into sampling units, strong evidence of wolverine tracks were found in 30% of units, weak evidence in a further 12% of units, and strong evidence of their absence in some 45% of units. The study by Landa et al., produced for the Convention on the Conservation of European Wildlife and Natural Habitats, concluded that there were around 265+ wolverines left in Sweden, 150+ in Norway, approximately 115 in Finland, and around 1500 in European Russia. Sæther et al. give slightly higher figures for 1998-2000: around 326 individuals in Sweden and around 269 individuals in Norway. In Sweden, due to human factors, the wolverine population was in steep decline until they came under legal protection in 1969, the first such protection of wolverines to be instituted in a European country. By the late 1960s, there were few wolverines left, and they mostly inhabited a narrow strip along the Fig. 1. Wolverine Distribution Worldwide. Source: International Union for Conservation of Nature. Norwegian border. Since then, their numbers have grown to constitute what Landa et al. term a ‘stable, although limited’ population (13). A similar pattern has prevailed in Norway and Finland. In Finland, wolverines were protected in 1982, and there has been some recovery in their numbers, so that Landa et al. could comment that ‘The population is stable to slightly increasing’ (13). In Norway, the population, having once been ‘hunted to functional extinction in southern Norway’ (Landa et al., 13) is now limited to south-central Norway and parts of the country facing the Swedish border. It is possible that the current population is experiencing a slight decrease, due to killing, both legal and illegal. The idea that Norway’s wolverine population is not at all viable in the long-term, given present rates of human activity inhibiting this, has been underlined by other studies also. Sæther et al. analysed the viability of wolverine populations in Scandinavia, based on data from Sweden and Norway, using the guideline that a population must have at least 46 sexually-active females, as set out by the World Conservation Union in 2001. They monitored 37 radio-collared females to study trends of reproductive success, and used helicopters and snowmobiles to estimate the size of the total breeding population, and find dens (Sæther et al. 1004). Having carried out a Population Viability Analysis (PVA), Sæther et al. concluded that if current wolverine mortality trends continue in Norway, the wolverine populations in the north of the country will became endangered, and those in the south vulnerable also (1001). Indeed, they go so far as to state that with no immigration, ‘the rate of loss of wolverines in Norway due to various kinds of human activities will likely lead to rapid wolverine extinction’ (Sæther et al. 1011). Similar trends have also been proposed for wolverine populations elsewhere. Lofroth and Ott collected data from 1985-2004 for wolverine populations in British Columbia, Canada, and concluded that the government quotas for the annual numbers of wolverines to be harvested was incompatible with the ability of those regions to sustain viable populations. Lofroth and Ott proposed that the harvest was unsustainable in 15 of the 71 population units they monitored, and was only marginally sustainable in a further 5 (2193). When dealing with the question of why wolverines have disappeared from what were previously its southernmost habitats, Landa et al. suggest that this retraction was ‘probably due to persecution, deforestation and human development’ (12). There seems to be some consensus across the research papers produced on this topic that these factors continue to be the most salient in explaining the current trends in wolverine population levels and distribution, and that the effects of global warming have had little impact on wolverines. Lofroth and Ott, likewise, list possible reasons for the retraction of the range of wolverine habitations, which, as they see it, ‘may include changing environmental conditions, changing food resources, human settlement and associated activity, harvesting, and persecution’ (2193). It is noteworthy that in most texts, it is direct human activity that is held most responsible for these trends. The possible effects of climate change are mentioned as a footnote, if at all. In Scandinavia, the human persecution of wolverine populations has mostly been due to their predation on sheep and reindeer, and the introduction, from the mid-19th century, of state bounties for wolverine hunters and trappers. Despite more recent legislation protecting wolverines, Sæther et al. report that due to their predatory activities, ‘there is a strong demand for the reduction of wolverine population size’ (1003). Abramov et al. make clear that ‘Ample forested lands and tundra with suitable prey stocks are available throughout much of this range’. The more pressing issue is the expansion of human exploitation of the land, especially in Europe, for habitation, agriculture, transport links, among less important uses. This has meant that the ample habitats ‘are not wilderness areas, and wolverines come into conflict with a low, but crucial, number of human land uses’ (Abramov et al.). In Norway, some 10,000 sheep are thought to be killed by wolverines each year. Wolverine predation is therefore a significant economic concern for the agricultural sector in that country, and indeed to some extent in neighbouring Sweden also. The Norwegian government has responded by appointing boards to determine quotas of wolverine harvests to be gathered each year, with the intention of lessening the threat to livestock. In British Columbia in Canada, also, the wolverine population has been managed with the intention of maintaining a viable population in the wild, as well as providing a harvest for trappers and hunters (Lofroth and Ott, 2193). Likewise, in Ontario, in 2004, the Ministry of Natural Resources listed wolverines as threatened on the State’s Species at Risk list, given that wolverines disappeared from southern parts of the State by the turn of the last century, and even from parts of the north in the past half-century (Magoun et al. 2221). In Scandinavia, wolverines were protected in Sweden from 1969, southern Norway from 1973, and the rest of Norway from 1982 (Sæther et al. 1002). Landa et al. also noted that the slow recovery rate for wolverines as a reason for their vulnerability. Once a wolverine population has been reduced, for whatever reason, it may be some years before they can regain their former levels, and that assumes that external conditions remain favourable. They are ‘slow breeders, with small litters’, of around 1-5 cubs, and individuals may only breed every few years, which ‘explains the observed low resilience of many wolverine populations’ (Landa et al. 20). Lofroth and Ott agree on the importance of such factors, noting that wolverines’ ‘resilience to external pressures may be limited by their low densities, large home ranges, and low reproductive capacity’ (2193). Many of these studies have had some deficiencies, and the lack of the availability of reliable, long-term data was a common factor for many of the research papers. However, there seems to be a general sort of consensus as to the major factors influencing wolverine population levels today. Summary Sources concerned with wolverine populations seem to agree that the most significant risk to the continued viability of wolverine populations, both today and over recent centuries generally, is the expansion of human land use into areas traditionally inhabited by buoyant wolverine populations. Historically, the retraction of wolverine habitats further and further north seems to have been caused by this trend. While ample habitats remain for wolverines, the key issue is that these habitats are often in areas where wolverine behaviour conflicts with human interests. Most often, this conflict is due to wolverine predation on domestic or semi-domestic livestock. There is an increasing tension in such areas between governments’ intention to preserve vulnerable wolverine populations, and their duty to protect the interests of their human populations. Conclusion It is clear that, thus far at least, the effects of climate change have not had a significant impact on wolverine populations. Abramov et al. put this quite plainly when they state that while ‘this species inhabits a zone that is particularly affected by climate change (IPCC International Climate Report 2005), habitat change or even loss is not taking place at such a rate to be considered a major threat to the wolverine’. Of course, we cannot assume, given the worrying predictions of future climate change, that environmental factors will not become more prominent among the issues affecting the wolverine. However, as it stands, the increased dissemination of human land uses, and the conflict this causes with wolverine populations, must be considered the most important issue. Bibliography Abramov, A. et al., “Gulo gulo”. The IUCN Red List of Threatened Species 2 (2010). Web. Landa, A. et al., “Action Plan for the conservation of Wolverines (Gulo gulo) in Europe”. Convention on the Conservation of European Wildlife and Natural Habitats: Nature and Environment, 115 (2005). Print. Lofroth, E.C. and Ott, P. K., “Assessment of the Sustainability of Wolverine Harvest in British Columbia, Canada”. The Journal of Wildlife Management 71.7 (2007): 2193-2200. Print. Magoun, A. J. et al., “Modeling Wolverine Occurrence Using Aerial Surveys of Tracks in Snow”. The Journal of Wildlife Management 71.7 (2007): 2221-2229. Print. Sæther, B. E. et al. “Management Strategies for the Wolverine in Scandinavia”. The Journal of Wildlife Management 69.3 (2005): 1001-1014. Print. Read More