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Tristan Andrew, Chase Beausoleil, Alex Davidson, and Ciara Moroney

Abstract

What can we learn from threats facing the arctic fox (Vulpes lagopus) to prevent future endangerment of species worldwide? The arctic fox is a keystone species who provides various ecosystem services that both maintain the health and prevent the collapse of the tundra. Therefore, preventing its endangerment would simultaneously conserve local environments and other arctic species. After conducting interviews and analyzing many scientific sources, we organized threats facing this species into three categories: food availability, predation, and viable geographic range. This chapter explores the importance of understanding threats to the arctic fox and how it can help other keystone species.

Background

The arctic fox (Figure 1) resides primarily in Canada, Scandinavia, Iceland, and Greenland (Angerbjörn & Tannerfeldt, 2014). It is a small species with a white or blue/gray coat in the winter and a tan or cream coat in the summer. The color change of the fur coat is to help camouflage the fox with its environment, aiding in protection from predators and ease in catching prey. The diet of the arctic fox mainly consists of lemmings and leftover seal carcasses abandoned by polar bears on the arctic sea ice (Angerbjörn et al., 1999).

The arctic fox is being severely impacted by climate change in numerous ways, including decreased food supply and habitat loss. Although the arctic fox is not currently officially classified as endangered, it does not mean the threats it is facing should not be taken seriously (S. Ámundason, personal communication, November 10, 2020). The arctic fox’s primary role in the arctic ecosystem is as an ecosystem engineer, which means its presence greatly impacts and influences the health of the entire ecosystem. The arctic fox fixes nitrogen in the ground around its den, promoting the growth of arctic shrubbery and other vegetation, which provides a source of food for both the arctic fox and many other species in the tundra (Gharajehdaghipour et al., 2016). The endangerment of the arctic fox would alter the entire ecosystem, with one effect being the reduced vegetation present and subsequently reduced food availability for primary consumers in the tundra (Graae et al., 2004). The investigation of the threats the arctic fox is facing could spread awareness of the importance of keystone species in all ecosystems and the long-term impacts of its endangerment across arctic biomes. Countries and organizations could be motivated to research threats and design precautionary conservation programs for keystone species that are not on the brink of extinction yet, but whose survival is critical for conserving complex ecosystems.

Our Research Process

In order to conduct research on the arctic fox for this project, we primarily performed an analysis of scientific literature. We gathered a large body of various scientific sources that we were able to use to learn about the different facets of the issue at hand. We were then able to synthesize these ideas to layout our research in a manner conducive to our project. At the beginning of our research process, we planned to identify climate change as the primary threat to the species because it catalyzes many of the threats to this species. However, throughout our research we realized this would be an almost insurmountable threat to address, so we turned to categorizing the large threats into three sections: food availability, predation, and viable geographic range. These sections better allowed us to analyze the issues and critically consider solutions that could be proposed.

In addition to scientific sources, we reached out to several experts in our field and were fortunate enough to conduct interviews with two: John Bockstoce (author) and Sæmundur Ámundason (Arctic Fox Centre Manager). These interviews helped us continue our research and investigate new topics that we had not considered before, such as researching the adaptability of the arctic fox species to climate changes in the past and searching for information on how increased human presence in the arctic tundra due to rising global temperatures is threatening the arctic fox.

Viable Geographic Range

Climate change is an overarching threat to not only the arctic fox but all species around the world. Containing the impacts of climate change proves to be a rather challenging task but understanding its complex effects in arctic environments is critical to planning conservation efforts in the future. One major way in which this is affecting the arctic is through habitat loss. While there are many facets to this issue, the primary problem comes from the northward movement of the boreal forest (Figure 2). As temperatures continue to increase in the arctic, the boreal forest expands further into the tundra and therefore into arctic fox territory. The warmer climate of the boreal forest is not able to provide a suitable environment in which the arctic fox could survive (Elmhagen et al., 2015). Because of this, the expanding northward movement of the boreal forest reducing the size of the arctic tundra is subsequently decreasing and compressing the geographic range of the arctic fox (Chapin, 2007).

Another contributing factor to the habitat loss for the arctic fox is a resident of the boreal forest, the red fox (Vulpes vulpes). The red fox is a species that would not be able to survive in the tundra region normally, but climate change has allowed for the red fox to move into the tundra. As will be expanded upon later, the red fox creates competition with the arctic fox for many resources, food being a primary one. In addition, the red fox also competes with the arctic fox for den space. (Rudzinski et al., 1982). The decrease in den occupancy of the arctic fox is detrimental to the population as the fox has less protection from predators and is discouraged from reproducing (Rodnikova et al., 2011).

A final facet that is decreasing the geographic range of the arctic fox is sea ice depletion. With the constantly increasing global temperatures, arctic sea ice has been melting at a rapid rate that continues to grow. Sea ice is an important aspect of the arctic fox’s habitat as it allows the arctic fox uses to traverse the tundra region which allows for higher biodiversity and population spread within the species (Roth, 2003; Geffen et al., 2007). Additionally, the arctic fox uses the sea ice for hunting purposes, gaining access to the animal carcasses left on the sea ice by polar bears and other arctic predators (Greenpeace International, 2019). Without sea ice, the arctic fox’s habitat size would be greatly restricted. Overall, the distribution range of the arctic fox is decreasing and will continue to decrease unless actions are taken to combat it.

Predation

As previously mentioned, the red fox proves to be a large threat to the arctic fox. Although the red fox is in the same species group as the arctic fox, these two animals are vastly different. For the two species to coexist, there must be a harsh environment or low ecosystem productivity to counteract the dominance of the red fox. As a result of the warmer winters and increased food availability, the red fox has been able to expand in numbers and geographic range as the changing environment and expansion of the boreal forest is providing suitable habitat for the red fox (Figure 3) (Post et al., 2009). The reason for recent expansion into the tundra is because the red fox has a higher energy burden than that of the arctic fox (Gallant et al., 2020). This means that the red fox requires more energy to sustain its predatory lifestyle, and when the winters are warmer less of that energy needed for hunting is used for keeping warm. This allows extra energy for the species to work on expanding its geographic reach and reproducing. This expansion of the red has proved to be detrimental to the arctic fox.

One of the main problems is the fact that the red fox is a host for parasites such as sarcoptic mange and fox tapeworm, as well as contagious and lethal diseases like arctic rabies (Norén et al., 2017). The introduction of these parasites to the species brings forward new and unfamiliar diseases, which could potentially be fatal. Furthermore, the two foxes vary in size, with the red fox reaching weights twice as high, while also reaching lengths up to 70% larger than that of the arctic fox (Gallant et al., 2012). Therefore, the red fox proves to be a new predator in the already scarce tundra. This addition of a new predator adds to the strain the arctic fox is experiencing because it is being hunted more frequently and the young foxes have a more difficult time surviving into adulthood. The red fox also brings with it increased competition for food and resources, forcing the arctic fox to retreat to higher altitudes on the mountain tundra where the red fox has more difficulty surviving (Elmhagen et al., 2002). This competition for food is caused by the diet overlap of the two species. Although the two species have a large variation in their diets, their food-niche tends to overlap during most summers, leaning towards lemmings, voles, and similar small species. On top of that, the red fox needs much more food and terrain to sustain itself (Gallant et al., 2012). The arctic fox consumes lemmings more frequently than red foxes do, but with the diet overlap, the decrease in the lemming population poses a threat to the arctic fox’s food availability (Elmhagen et al., 2002). Overall, the introduction of the red fox to the tundra is providing new predation and competition for the arctic fox, which could be harmful to the population moving forward.

Food Availability

Lemmus amurensis, more commonly known as the lemming, is the primary food source for the arctic fox and as a result, population cycles of the arctic fox are strongly affected by microtine rodent populations (lemmings and voles (Mus cypriacus); Roth, 2003). The lemming follows a persistent 4-year population cycle, meaning every four years the lemming population will spike and then decrease again for the next few years (Archibald, 2019). This is believed to result from the interaction of intrinsic factors and extrinsic factors (Archibald, 2019). Therefore, during these times, harvest records imply that the local arctic fox population also cycles regularly and dramatically (Roth, 2003). During the lows in these cycles, arctic fox reproductive success is low, with them waiting until the peak year in the cycle, where there is a more plentiful food source, to reproduce (Ims et al., 2017). When the lemming population is down, the arctic fox turns to marine resources. While it was found that there is technically an abundance of marine resources available to the arctic fox, there is also steeper competition for the resources, leading the arctic fox to also hunt seal pups (Pusa hispida) as a source of food (Roth, 2003). However, this poses a problem because not only are arctic foxes hunting seal pups. Polar bears (Ursus maritimus) and the red fox are as well, leading to increased predation of seal pups. The arctic fox does, however, feed on the left-over seal carcasses that polar bears and red foxes leave (Bockstoce, 2018), but a depletion in sea ice is diminishing this access to food.

During a study from 2004-2005 in the arctic ocean, it was found that the amount of perennial sea ice in the East Arctic Ocean decreased nearly one half with an abrupt reduction of 0.95*106 km2 (Nghiem et al., 2006). This is very detrimental to the diet and the safety of the arctic fox, as they use this sea ice, especially in the eastern arctic ocean, to travel, find leftover carcasses, and escape predators. The detrimental effects cause changes in the behavior of arctic foxes and occasionally lead to them becoming nomadic in winters when local foods are scarce (Roth, 2003). This means that instead of staying near their dens in the winter they wander around, returning to den sites in the spring for breeding (Roth, 2003). This causes unusual breeding habits, which can decrease the population of the fox.

Breeding in the spring poses a threat to the newborn pups as they can become prey for other scavengers and predators in the arctic. The large litters of pups do not allow for much protection as it is hard for one mother to protect up to 14 pups at once. Therefore, larger birds such as ravens (Corvus corax) pose a threat to the pups. This is on rare occasions; however, ravens are opportunistic predators and scavengers (Chevallier et al., 2016), meaning they will feed on anything that is already dead or anything they think they could takedown. Therefore, on some occasions, they attempt to take on small arctic fox pups. However, when they are not doing this, they tend to feed mostly on small rodents and complement their diet with scavenged items, such as carrion left by larger predators (Chevallier et al., 2016). Not only do ravens pose a threat to the reproduction of the arctic fox, but their remarkably similar diet to the arctic fox means there is even less food during the non-peak years of the rodents. This decreases the arctic fox’s food availability, which then causes the foxes being affected to become nomadic. As discussed, nomadic foxes pose a further threat to the species because this behavior leaves the foxes and their pups vulnerable to larger predators. When in packs, arctic foxes can take down larger prey and retain greater chances of warding off predators. However, when these foxes refrain from staying in groups due to decreased food and resource availability, they further endanger themselves (Elmhagen, 2014).

Threats Combined

Our research proved that the threats being faced by the arctic fox are vast and seemingly endless. Every minor problem is intertwined with a dozen other problems that form one large web of issues harming the species (Figure 4). A simple decrease in the lemming population or the gradual expansion of the red fox population would individually not be enough to drive the species to endangerment or extinction. However, part of the species’ plight is that there is no one threat acting alone. Climate change has initiated the gradual warming of the world’s climate, which is slowly allowing the boreal forest to creep into territory previously occupied by the arctic tundra (Chapin et al., 2010). As mentioned, the boreal forest is not a suitable habitat for the arctic fox to survive in. However, it is a particularly good habitat for the red fox to survive in. So, with the growth and expansion of the boreal forest, the red fox is provided with better means to invade previously occupied arctic fox territory (Elmhagen, 2015). Additionally, the lemming is reliant upon a frigid climate to survive, so climate change causing an increase in temperature worldwide is severely harming the ability of the lemming to thrive (Ims et al., 2011). This is one driver of the decrease in lemming populations, but so is the arrival of the red fox, which also preys on lemmings as a source of food. Historically, in years when the lemming population was low, arctic foxes would not reproduce as much as they would in a different year that contained larger lemming populations, and this still holds true (Roth, 2003). So, this decrease in food access is causing the arctic fox to reproduce more slowly while also being hunted by predators at a higher rate, causing intensified stress on their population. All the issues outlined, and more, are compounding one another and working together to create the perfect environment for a substantial decline in the arctic fox population to be observed in the not-so-distant future, which could subsequently prove to be detrimental to the arctic ecosystem.

Despite the inexhaustible amount of information, we discovered describing serious threats to the arctic fox that support the concept of the eventual endangerment and potential extinction of the species, author John Bockstoce, who is one of the experts in the field interviewed by the team, still believes that the arctic fox species is not and will not be susceptible to extinction, or even endangerment. Bockstoce claims that the arctic fox is too adaptable to its surrounding environment to be largely negatively affected by any major changes in temperature or arctic sea ice distribution. Furthermore, the author claims that because arctic foxes are scavengers, the species will consume almost anything, therefore discrediting the threat of reducing food sources as lemming populations and food availability on arctic sea ice decrease (J. Bockstoce, personal communication, November 6, 2020). However, an article by author Fuentes-Hurtado opposes Bockstoce’s claim while supporting the findings our team found in our research.

Fuentes-Hurtado’s article claims that arctic foxes are more sensitive to changing climate than previously assumed. An “ecological niche modeling approach” was used to study the arctic fox population at the end of the Pleistocene epoch, which was a time also known as the “Great Ice Age” due to many periods of glaciations throughout this time (Fuentes-Hurtado et al., 2016). By studying the ancient DNA of this fox species in Europe that dated back to the Pleistocene epoch, this study concluded that the arctic fox species became extinct in Europe directly following this epoch as global climates changed, and temperatures rose. The Pleistocene epoch consisted of vast tundra environments and expansive sea ice. When temperatures rose as the epoch ended, this tundra environment that the fox thrives in decreased in size, threatening the species, and eventually causing its extinction in Europe. Understanding that arctic foxes became extinct in a specific geographic location in the past is especially important because the extinction identifies the possibility of changing global temperatures threatening the arctic fox species to the point of extinction. Luckily in the past, the species was able to survive the end of the Pleistocene epoch due to their large geographic range in which populations of the species remained in favorable conditions and survived (Fuentes-Hurtado et al., 2016). However, if global temperatures today continue to rise and all viable habitats for this species continue to decrease as tundra biomes shrink, the species may yet again be threatened by extinction, although this time more absolute.

Beyond the Arctic Fox

The safety of keystone species is integral to the health and development of every ecosystem on this planet. They provide a multitude of ecosystem services ranging from contributing to nutrient cycling, maintaining a healthy balance in the populations of some species, dispersing seeds of local vegetation, being a food source for other species, and more (Graae et al., 2004). Any threat to a keystone species such as the arctic fox is a threat to the future of the ecosystem itself. However, this plight is not unique to the arctic fox. From sea otters dealing with changes in aquatic conditions to bees facing massive habitat loss, keystone species around the world are beginning to face worsening conditions that can be attributed to climate change, human interference, and more. Right now, many of these problems are in stages that can be remedied with the right education and resources. However, if they are pushed to the back burner until the species is facing permanent extinction, it will likely be too late for any real changes to be made. Through bringing awareness to the current struggle of the arctic fox and continuing to research and monitor the development of their state, perhaps people around the globe will begin to take notice of other species who are facing smaller problems that can be acknowledged now before it is too late.

What Now?

The most efficient way to help the arctic fox would be to fix climate change, as that plays a hand in the formation of all the threats outlined. However, that is relatively impractical and not something that can be fixed immediately. That being said, there are actions that can be taken at various levels to help improve conditions for the fox as much as possible. In the field, one thing that can help the species is controlling the expansion and growth of the red fox population in areas where it interacts with the arctic fox (Larm et al., 2018). Studies conducted have proven that supplementing the red fox’s food source with outside food can take pressure off the arctic fox as a source of prey, and even light hunting of the species to decrease numbers can have positive impacts on the arctic fox species (Larm et al., 2018). Similarly, lemming populations can be fostered to help the recovery of their abundance in nature. By making sure that the wildlife the lemmings depend on for food is healthy and abundant, the population can be helped to regrow itself to where it was. The supplementing of the red fox’s diet will also help the lemming population because the red fox will not need to eat as many lemmings and that will decrease the competition the red fox is facing for food. These changes in the field are not immediate, but they can produce positive short-term results, that if maintained can continue to support the arctic fox population well into the future.

On a more global scale, educating the public is one of the most important actions that can be taken. This likely will not have a direct or immediate impact on the arctic fox species but can foster long-term change that will be beneficial both for the arctic fox and many other species. Studies have shown that members of the general public who are more educated on issues of endangerment and climate change are substantially more likely to make changes in their day-to-day life that will positively impact wildlife and are also more likely to support larger legislative actions that can help the wildlife around them (S. Ámundason, personal communication, November 10, 2020). Overall, continuing to monitor the arctic fox population will prove to be important, as this can show the effectiveness of strategies being implemented to help with their refinement both for the arctic fox and other keystone species around the world in the future.

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