Abstract
Twenty beavers Castor canadensis (Castoridae) were initially introduced in the Argentinean portion of Tierra del Fuego Island, from where they have occupied most of the Fuegian Archipelago and even reached the continent. This invasion is causing great damage to the subantarctic forest ecosystems, and it is not known how fast the species is spreading. While there is an estimation of this advance using interviews, it is not known how reliable these are and they cannot be made in remote areas. On the mainland, where beavers were present, their date of arrival was estimated using interviews and dendrochronology, and the dates obtained by both methods were compared for each site. Differences were found among the groups of respondents, according to property size, in their ability to detect changes in the environment made by beavers. The dates of arrival estimated through dendrochronology are 23 years prior to those determined through surveys, and they generate a potential route of arrival from the Fuegian Archipelago and migration in the mainland. This route is more parsimonious than the route of dispersal generated through interviews. Since it was determined that there is no relationship between the dates estimated through surveys and dendrochronology, it is not possible to determine how much lag there is from the time when changes in the environment are produced by beavers and the time when people notice this change. Our results indicate that this lag may not be constant among different groups of people.
Highlights
Twenty beavers Castor canadensis (Castoridae) were initially introduced in the Argentinean portion of Tierra del Fuego Island, from where they have occupied most of the Fuegian Archipelago and even reached the continent
These dates were considered as the tentative arrival dates of beavers at each site and were used to generate a hypothetical map of beaver dispersal from known points of presence on the islands of Tierra del Fuego and Dawson and movement across the continent (Figure 3)
The migration of Castor canadensis would have occurred from Caleta River crossing through Parrillar Lake and dispersed by rivers that flow into the Strait of Magellan
Summary
Twenty beavers Castor canadensis (Castoridae) were initially introduced in the Argentinean portion of Tierra del Fuego Island, from where they have occupied most of the Fuegian Archipelago and even reached the continent This invasion is causing great damage to the subantarctic forest ecosystems, and it is not known how fast the species is spreading. Castor canadensis (Castoridae) is an invasive species in southern South America, and it has been classified as Graells et al Revista Chilena de Historia Natural (2015) 88:3 and prevent the natural regeneration of forests and aquatic ecosystems (Anderson et al 2006; Martínez Pastur et al 2006) In such conditions, only the seedlings of Nothofagus antarctica are capable to establish successfully, which could help the regeneration of the riparian forest, but only in the long term (Anderson et al 2009). This difference has been interpreted as a preference of the species for forested habitat environment over the steppe (Skewes et al 2006)
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