Print PageThe American mink (Neovison vison) is a semi-aquatic mustelid that was released on Tierra del Fuego Island in the 1940’s, subsequently spreading throughout the whole archipelago. Its introduction to other insular systems around the world has caused the reduction and displacement of native competitors. The southern river otter (Lontra provocax) is an endangered aquatic mustelid, which is distributed along the sea channels of the region. Knowledge of interactions between these two potentials competitors is essential to conserve the native otter and control the exotic mink. Therefore, we evaluated abundance, distribution, habitat characteristics and diet of otter and mink along 248 km of the Argentine coast of the Beagle Channel in 600 m transects set every 5 km. We constructed a habitat suitability model for each species based on the location of signs (scats, tracks and dens) and habitat characteristics (vegetation type, shoreline slope, distance to water, human presence, signs of mink/otter presence), using generalized linear model (GLM). Scats were also collected for diet analysis. Habitat use and diet of both species were compared. Additionally, mink diet and abundance of signs were compared between places with or without otters.
Results/Conclusions
The GLM that best fit mink data included habitat type (forest and shrubland), distance to water and coastline slope. Mink presence was no related with human or otter presence. The GLM that best fit otter data included habitat type (forest and shrubland), coastline slope and human presence (negative effect) and unrelated to mink presence. Otter consumed more aquatic prey (95.4%) than mink (56.5%). No differences were found between the two mustelid species regarding type of marine prey consumed when analyzed at higher taxonomic levels (e.g., fish, crustaceans, etc.), but within each type, the species and individuals preyed upon by otter were bigger than those eaten by mink. Additionally, the mink consumed more terrestrial preys (mammals and insects) in areas with otter. Mink abundance was greater in areas without otters. Both species used the same habitat type along the Beagle Channel coast, but in the areas where they were found together the mink was less abundant than elsewhere and showed greater divergence of diet away from marine prey. We propose that the otter may outcompete and potentially could restrict the mink invasion. So the recovery of this native species would be one additional way to control the invasive mink population.
