Understanding the inter-specific dynamics of two co-existing predators in the Tierra del Fuego Archipelago: the native southern river otter and the exotic American mink

A VALENZUELA; A RAYA REY; L FASOLA; A SCHIAVINI

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2013 p. 645 - 656

1387-3547

Knowledge about interactions betweenendangered native southern river otters (Lontra provocax)and introduced American mink (Neovisonvison) is essential for effective management of bothspecies. We evaluated competition for spatial andtrophic niches between otter and mink in overlappingand non-overlapping areas, comparing distribution,habitat preference, diet and mink marking behavior.We surveyed otter and mink signs along 250 km ofBeagle Channel coastline. Habitat suitability modelswere constructed based on species presence/absenceand habitat characteristics, using generalized linearmodels. Feces were collected for diet analyses. Ottersused forested coasts with 12?32 shoreline slope andwithout human influence, and our evidence suggeststhey were not affected by mink presence. Minkpreferred forested and shrubland coasts with 10?28shoreline slope. Neither human influence nor otterpresence affected mink habitat occupation, but in thepresence of otters, mink left fewer signs. Ottersconsumed more aquatic prey than mink, and minkmodified their diet in the presence of otters, consumingmore exotic small terrestrial mammals and less fishas well as shifting to smaller and shallower fish speciesthat are less consumed by otters. Mink showed moreplastic, generalist behavior than otters, being moretolerant of human presence, using more habitat typesand having greater diet breadth. At the same time,otters apparently affect mink adversely and could helplimit their invasion in sympatric areas. Conservationand recovery of otters, therefore, may produce asecondary benefit of simultaneously reducing theeffect of mink, thereby providing an additional wayto control this exotic predator?s population.