By Peyton Stuart
Beavers, unsurprisingly, are not a native species to Latin America. Although they flourish in the biomes of North America, the drastic climate difference in South America inhibits this species from being able to survive in many countries. Today, despite this fact, there are over 100,000 beavers that have inhabited the Southern region of Argentina and Chile, specifically Tierra del Fuego. So, how did a North American species, evolved to survive in aquatic ecosystems and coniferous forests with colder climates and medium rainfall migrate through the unforgiving temperatures of the equator and down to the Southern tip of Chile?
In the mid 1940’s, the Argentinian government saw potential in a fur industry and hoped to draw people to inhabit its sparce, unpopulated Southern region. Flying in only 20 beavers in 1946, they did not envision the massive amounts of damage that this unsuspecting species would cause to both the environment and the economy (Davis, 2016). With no natural predators, the beaver population skyrocketed, growing by thousands per decade. By the 1960’s, the species had travelled into Chile and by the mid-1990’s, some beavers had even been spotted on islands across the Strait of Magellan (Gilliland, 2019). Although there were hopes of a booming fur trade, it was unsuccessful. Beaver pelts are not worth much compared to pelts of more popular game.
The kind of rapid spreading represented by this population, followed by the immense destruction that this population has caused in the past 75 years, has led to the North American Beaver being identified as an invasive species. As cited by the National Wildlife Federation, invasive species are species that are non-native to an area, “grow and reproduce quickly, and spread aggressively, with potential to cause harm” (Invasive Species, n.d.). As for transplantation, invasive species have many means for introduction to a new area. From as simple as an insect hitching a ride on travelling produce to the physical transportation of plants or animals to a new area, it can be exceedingly difficult to predict the impact of such an ecological change. Moreover, invasive species typically cause direct effects on the environment in which they live as well as many secondary, indirect effects. Due to competition and resource depletion, many invasive species diminish the populations of native organisms, sometimes driving them to extinction; “Approximately 42 percent of threatened or endangered species are at risk due to invasive species” (Invasive Species, n.d.). In most cases, the introduction of invasive species is detrimental because the species and the environment have not been able to coevolve together. Coevolution occurs between different species within the same area as they all adapt to the same ecosystem and discover their own niches in order to survive. Thus, an invasive species may not have predators in their new habitat, giving them an ecological advantage, or perhaps the “native wildlife may not have evolved defenses against the invader” if they are predatory (Invasive Species, n.d.). Compared to the millennia that took place for native species to find their place in the ecosystem, an invasive species can destroy it in a matter of decades. Nonetheless, they can also cause physical changes to the ecosystem and disrupt the food web. Even the smallest alteration in these ecological processes has the power to affect every organism within the ecosystem.
As for the beavers, while they are perfectly suited for certain ecosystems in North America, those of South America were not prepared for the arrival of the species. In terms of just foliage and tree cover alone, North American trees evolved defenses against the beavers; “trees like willow, cottonwood, American beech, and alder have all evolved responses to beaver chewing and flooding” (Gilliland, 2019). In Tierra del Fuego, beavers introduced only 75 years ago have wiped out 30% of the forests in the region (Davis, 2016). Even from space, the impact that the beavers have had on this area is so big that their dams can be seen from satellite images (Gilliland, 2019). Apart from this massive land disruption, the creation of these dams brings in new problems all together. Dams flood regions, drown certain wildlife, and even stunt native tree growth; “25% of the forest and 95% of the archipelago basins have been affected by beaver dams” (Poblete, 2017). Relating back to coevolution, the native species of this region were unprepared for beavers to begin to inhabit and control the area. In Patagonia, the general Southern region of Chile and Argentina, beavers have caused “the largest landscape-level alteration in subantarctic forests since the last ice age” (Gilliland, 2019). Now having travelled to other areas of the region, across many islands and even onto the mainland, both governments are concerned with further damage that the species could cause.
Besides just predominantly negative direct effects of the invasive beaver population, perhaps the most detrimental effect is not as obvious. As one invasive species begins to take over, steal resources, and destroy niches, they open an opportunity for other invasive species to come in as well to fill those ecosystem roles. In Tierra del Fuego, the introduction of beavers has led to the acquisition of both muskrats and minks, two additional non-native species (Gilliland, 2019). Although their impact on the environment is not as grand, they are still altering food webs, resource levels, and the entire ecosystem in general. This “invasive meltdown process” is a difficult spiral to get out of as multiple invasive species are much harder to control than just one.
Apart from ecological disruption, beavers are harming the economies of both Argentina and Chile. Their deforestation habits have led to massive amounts of damage to infrastructure; “damage caused by beavers costs Argentina alone $66 million a year” (Gilliland, 2019). Another motive to stop their spread. Unfortunately, for these countries, beavers are both intelligent and prevalent as an invasive species. Although efforts have been made to diminish their population in the region, many strategies have failed. Moving forward, the governments have proposed a few ideas to help mitigate the impact of this species. First, both governments encouraged the hunting of beavers across the region. Even offering incentives, they hoped to spark some interest in controlling the beaver population. For these governments, in order to control such a rampant problem, total cooperation is needed. While it may be expected that the landowners would not want the government to directly interfere with their land, surprisingly, many expressed the contrary; “landowners preferred a program that would allow the program managers to have access and complete control over beaver eradication on private land” (Davis, 2016). Although many are on board with this plan, some landowners rely on the beaver population for their own micro-industries, such as ecotourism. Ultimately, if everybody is not on board, controlling the population of this invasive species becomes increasingly difficult.
As unsuspecting as they may seem, many invasive species critically damage the ecosystems they commandeer. For beavers in South America, this includes habitat destruction, landscape modification, and economic disruption. While the Chilean and Argentinian governments struggle to garner support to help control the beaver population, it is only a matter of time before the consequences become irreversible.
Davis, L. (2016, January 11). Researchers help design incentive programs to rid South America of invasive beaver. VTx | Virginia Tech. https://vtx.vt.edu/articles/2016/01/011116-cnre-beavereradication.html
Gilliland, H. C. (2019, July 25). Argentina brought beavers to Tierra del Fuego. It was not a good idea. National Geographic. https://www.nationalgeographic.com/animals/article/beaver-overpopulation...
Invasive Species. (n.d.). National Wildlife Federation. https://www.nwf.org/Educational-Resources/Wildlife-Guide/Threats-to-Wild....
Poblete, J. (2017, January 6). Beavers imported from Canada are threatening the primeval forests of Patagonia. Los Angeles Times. https://www.latimes.com/world/mexico-americas/la-fg-beavers-tierra-del-f...