Alejandro Pietrek

Predicting and Managing the Spread of Invasive Beavers in the Heterogeneous Landscapes of Patagonia

Releasing a radiotagged adult in the forest of Tierra del Fuego.

A beaver in the windy and treeless patagonian steppe.

New lodges are found often in the steppe.

Town/RegionCountryCategoriesDate
Tierra del FuegoArgentinaCentral and Latin America, Mammals27 Oct 2010

The Island of Tierra del Fuego, in southern Argentina and Chile, harbors some of the most pristine subantartic ecosystems in the world. Extense old growth forests near the Andes, peat bogs, meadows, glaciers and a vast hydrographical network create a unique landscape for wildlife. One of the major threats to this biodiversity is the introduction of invasive species, most notably the North American Beaver (Castor canadensis).

Beaver are responsible for the most drastic landscape alteration in Tierra del Fuego since the last glacial age, affecting not only the hydrology and composition of the southern beech forest, but more importantly allowing other exotic species to invade the ecosystem. The species had arrived on the mainland of Chile by 1990, raising concerns about a further expansion throughout Patagonia.

This highlights the need for better computer-based forecasting models to predict the spread of the invasion and to guide managers seeking to slow the northward expansion of the species. Most invasion models that have been produced up to now have ignored habitat heterogeneity which presumably plays an important role in heterogeneous landscapes such as Tierra del Fuego.

In this study we propose to combine Geographical Information Systems (GIS) tools, field data using radiotelemetry, and novel computational modeling approaches to extrapolate habitat-specific population and dispersal parameters into rates of invasion in different habitats. Our main objective is to build an invasion model that includes habitat heterogeneity to more accurately forecast the invasion of beaver in Patagonia and ultimately, prevent its further spread in Argentina and Chile.

For further information contact alejandro.pietrek@duke.edu

Project Update: May 2011

In our first fieldwork season, we have found and surveyed 30 beaver colonies distributed in two study sites with contrasting habitat characteristics: forest and steppe. These two habitats are the most representative of Patagonia and estimation of site-specific population parameters will enable a more accurate modelling of the invasion. We observed more than 70 beavers in these colonies and we marked 15 individuals (kits, yearlings, sub adults and adults) to study their dispersal and estimate survival using radio-telemetry. Direct observation data using specific lures has also allowed us to obtain fecundity data for each colony. For the next season we are planning to survey additional colonies and increase the number of radio-tagged individuals.

Final Report

Read more about the activities undertaken and findings of this project in the final report below.

File DownloadSize
Final Report701 KB
2nd RSG Grant Awarded

Congratulations to Alejandro for his second RSG, to read about this project http://www.ruffordsmallgrants.org/rsg/projects/alejandro_pietrek_0


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