Habitat use by invasive North American beavers during intermediate and long-term colonization periods in southern Patagonia

ERNESTO F. DAVIS; ALEJANDRO E. J. VALENZUELA; SILVIA MURCIA; CHRISTOPHER B. ANDERSON

MASTOZOOLOGíA NEOTROPICAL

UNIDAD DE ZOOLOGÍA Y ECOLOGÍA ANIMAL, INSTITUTO ARGENTINO DE INVESTIGACIÓN DE LAS ZONAS ARIDAS, CRICYT, CONICET

Lugar: Mendoza; Año: 2016 vol. 23 p. 51 - 61

0327-9383

Since their introduction to southern Patagonia in 1946, North American beavers (Castor canadensis)have become a major impact to streams and forests. Scientists and managers now call for their eradication,requiring research to orient actions. John et al. (2010) showed that predicting beaver presence, which is crucialto plan eradication efforts, varies throughout colonization time (initial=unpredictable occupation of random sites;intermediate=predictable occupation of optimal sites; long-term=unpredictable occupation of sub-optimal locations).Beaver presence/absence and habitat variables (geomorphology, soil, and vegetation) were measured inthe field and from satellite images in sites colonized at intermediate (Brunswick Peninsula ~1994) and long-term(Navarino Island ~1960) periods to predict this species? habitat use. Habitat suitability models were constructedusing generalized linear models with those variables significantly different between sites with and withoutbeaver. As hypothesized, a significant explanatory habitat model could not be developed for long-term occupationsites. However, beaver presence was predictable at intermediate colonization sites, and the best significantmodel included only river sinuosity and explained 74% of data variability. The model suggested that beaversused areas with greater river sinuosity, which could be measured from satellite images. Since remotely-sensedinformation requires less field effort, this approach could be useful in southern Patagonia?s remote areas, whereaccess is difficult. Additionally, these findings highlight the overall difficulty of planning a large-scale beavereradication program and predicting beaver habitat use across a gradient of habitat types and colonization stages.