Building alliances between research and management to better control and mitigate the impacts of an invasive ecosystem engineer: the pioneering example of the North American beaver in the Fuegian Archipelago of Chile and Argentina

ANDERSON, CB; SOTO, N; CABELLO, JL; WALLEM, PK; MARTÍNEZ PASTUR, G; LENCINAS, MV; ANTÚNEZ, D; DAVIS, E

A Handbook of Global Freshwater Invasive Species

Earthscan Publishing

Lugar: London; Año: 2011; p. 347 - 359

The North American (or Canadian) beaver (Castor canadensis) is the largest rodent native to North America, being found in an extensive range from northern Canada to northern Mexico. It has only one other extant congener, C. fiber, distributed originally throughout western and northern Eurasia. Both species affect extensive areas by ?engineering? stream and riparian habitat through their habits of dam building and cutting streamside vegetation. They were also both prized for their pelts, leading to near extinction in their native ranges. Castor canadensis was hunted heavily and locally extirpated throughout North America by the late 1800s; subsequent conservation and restoration efforts succeeded in reintroducing the species in much of its native range by the mid- to late 20th century. Simultaneously, in the 1940s and 1950s, efforts in various countries sought to introduce North American beavers outside of their native range for the perceived commercial value of its fur, including countries in Europe (e.g. Finland, Poland, Austria and Russia), where the native C. fiber had been decimated, and Chile and Argentina, where no native species occupied a similar niche. Due to the unique nature of the introduction of beavers to southern South America, this chapter will focus on the socioecological role of this invasive exotic species in sub-Antarctic forests and the policy-research response of local and international managers and scientists. The sub-Antarctic archipelago, shared between Chile and Argentina, presents a paradox. On one hand, portions of this ecoregion are some of the least disturbed ecosystems on the planet (i.e. low human population density, highly intact native vegetation cover and over 50 per cent of its territory falling within the system of state protected areas), while at the same time, it experiences pressing global environmental threats such as invasive alien species, climate change, the ozone hole and rapid commercial development, including tourism and salmon farming. The North American beaver has large impacts across the Tierra del Fuego and Cape Horn Archipelagos. The species was introduced in a single release of 25 pairs in 1946 by the Argentine government to Isla Grande in efforts to create a fur industry. Curiously though the hunting of beavers was not legally sanctioned until 1981 in Argentina and during that interval the population expanded south and west into Chile. By the 1960s beavers had crossed the Beagle Channel, occupying what is today the Cape Horn Biosphere Reserve and progressively colonizing the neighbouring islands of Navarino, Hoste, Picton, Nueva and Lennox. Additionally, the mainland was invaded by the mid-1990s, especially in the area of the Brunswick Peninsula. To date, beavers have not been confirmed in the Wollaston Islands (Cape Horn National Park) and the far western portion of the archipelago (Agostini National Park).