Coexistence between the southern river otter and the alien invasive North American mink in marine habitats of southern Chile

Abstract

The interaction between native and introduced predators can be an important determinant of the success of introduced species and of the magnitude of their effects. In Europe, it has been shown that the American mink Neovison vison can be affected by native competitors; however, such evidence has not been found in South America. We studied the southern river otter Lontra provocax and the American mink at five marine sites, where they coexisted, and at one freshwater site, where only mink were present, in southern Chile. We used the signs of both species to study their habitat use and diet, and radio tracking to study their activity patterns. The results indicated that otters and minks tended to use different habitats in marine environments, the otter favouring littoral areas that are rocky and steep while the mink favours areas of gravel with a gently sloping intertidal zone. These differences were also reflected in their diets. At one of the coastal sites where the diet of the two species was similar, the activity pattern of minks was mostly diurnal, which is unusual. While differential habitat use may be the way through which the American mink is able to coexist with the southern river otter in coastal habitats of southern Chile, it is possible that otters are having an effect on individual minks by affecting their activity patterns, although more observations are needed to confirm this hypothesis.

Assessment of the efficiency in trapping North American mink (Neovison vison) for population control in Patagonia

“…The average annual temperature is below 10°C (Veblen and Schlegel 1982; Toledo and Zapater 1989). River geomorphology was classified according to Montogomery and Buffington (1998) and seashore geomorphology according to Medina-Vogel et al (2013).…”

“…Depending on the study site, due to logistical constrains, it took between 3 and 9 days to deploy all traps, and each trapping campaign was between 4 to 23 days long and ended after 4 consecutive days without any mink trapped and no field signs found, or when some traps were stolen. Previous studies showed the strong preference of minks on marking under dense vegetation, steep river banks, behind rocks and under roots, in narrow passages, and in major intensity in shallow seashores (Medina 1997;Medina-Vogel et al 2013). Hence, cage traps were set close or inside these features and normally a couple of meters away from the water.…”

“…Since then, the species' 'feral' status has been considered as a problem to the preservation of native wildlife in Chile (Iriarte et al 2005). In fact, mink is implicated in a myriad of conservation issues for birds and small mammals in Argentina and Chile and occurs in both freshwater and marine habitats (Medina 1997;Fasola et al 2009;Medina-Vogel et al 2013). The spread of invasive North American mink in Patagonia with its devastating impact on native biodiversity has produced a growing realization of the need of an active management to minimize such impacts (Rozzi and Sherriffs 2003;Davis et al 2012).…”

High prevalence of pathogenic Leptospira in alien American mink (Neovison vison) in Patagonia

“…Minks likely become infected after preying on rodents. In fact, studies carried out in the same region as our study demonstrate that mink preys heavily on rodents (Medina-Vogel et al 2013), and that rodents may become infected by contact with garbage and contaminated water (Smith and Rochowski 2011). In the south of Chile, rodents present high rates of Leptospira infection (Zunino and Pizarro 2007).…”

Caracterización de la comunidad de mamíferos de un área remota del sur de Chile mediante el uso combinado de metodologías

“…El visón americano colonizó distintas áreas del sur de Chile tras la instalación de granjas peleteras desde donde se escaparon o fueron liberados cuando su explotación económica dejó de ser rentable (Iriarte 2008). Actualmente se desconoce el efecto de este carnívoro en los depredadores nativos de Huinay, así como en sus presas principales, por lo que sería interesante su estudio, como se ha hecho en otras zonas del sur de Chile (Medina-Vogel et al 2013). Existe un considerable debate sobre la utilidad de las encuestas como alternativa a los tradicionales estudios ecológicos de campo.…”