American mink

About: American mink is a research topic. Over the lifetime, 667 publications have been published within this topic receiving 12901 citations. The topic is also known as: Neovison vison & Mustela vison.

Character Displacement, Sexual Dimprphism, and Morphological Variation among British and Irish Mustelids

Abstract: Five native terrestrial mustelids are found in Great Britain. Only three of these occur in Ireland. Farmed American mink have recently established feral populations on both islands. We studied inter- and intraspecific size relationships, sexual size dimor- phism, and morphological variation among these mustelids. We viewed each sex as a separate morphospecies, skull length as a measure of body size, and the upper canine tooth as the organ used to kill prey. Geographic variation was low in both islands, so we considered the mustelid population of each island a single unit. Community-wide character displacement (evidenced by equal size ratios) was found among British mustelids for canine diameter. For skull length it was seen only when the largely vermivorous badger was excluded. When we added feral mink the regular pattern disappeared, but when we substituted the mink for the polecat, which is now restricted to parts of Wales and adjacent England, community-wide character displacement was man- ifest. For Irish mustelids size ratios were not equal, but the pattern for canines was more regular than for skull lengths. Adding the local feral mink did not result in a regular pattern, but addition of the mink and exclusion of the badger yielded equal ratios for skull length but not for canines. These patterns plus published empirical data support a hypothesis of prey size partitioning. The significant differences in size between some of the British and Irish populations of the same morphospecies suggest the possibility of ecological release among Irish mustelids, whose populations originally derive from British ones. In particular, canine sexual size dimorphism is greater for Irish pine martens, stoats, and mink, as would be expected if there were fewer competitors. For the marten and the stoat, Irish females have evolved to be strikingly smaller than their British counterparts, in each case approximating the size of the male of a missing species (polecat for the marten, weasel for the stoat). For skull length there is no consistent pattern. Finally, morphological variation is greater in Ireland for five of six morphospecies, as predicted by the niche-variation hypothesis.

Invaders without frontiers: cross-border invasions of exotic mammals

Abstract: We address cross-border mammal invasions between Chilean and Argentine Patagonia, providing a detailed history of the introductions, subsequent spread (and spread rate when documented), and current limits of mammal invasions. The eight species involved are the following: European hare (Lepus europaeus), European rabbit (Oryctolagus cuniculus), wild boar (Sus scrofa), and red deer (Cervus elaphus) were all introduced from Europe (Austria, France, Germany, and Spain) to either or both Chilean and Argentine Patagonia. American beaver (Castor canadensis) and muskrat (Ondatra zibethicus) were introduced from Canada to Argentine Tierra del Fuego Island (shared with Chile). The American mink (Mustela vison) apparently was brought from the United States of America to both Chilean and Argentine Patagonia, independently. The native grey fox (Pseudalopex griseus) was introduced from Chilean to Argentine Tierra del Fuego. Few spread rates are available: the lowest are 10 km/yr and correspond to American beaver and American mink; intermediate rates are observed in muskrat and rather questionably, in grey fox; the highest rates (10–20 km/yr) are found among European hare and European rabbit. Because of their frequent migration, it is difficult to estimate the natural spread rate for wild boar and red deer. Not all mammal invasions in Chilean and Argentine Patagonia have been methodical advances of species; some involve an overlap of invasion fronts, with advances and retreats, and perhaps with re-invasions to different areas of either country. Because national policies with regard to introduced species may differ between countries sharing porous borders, it seems advisable to coordinate such policies in order to prevent the entry of unwelcome invaders.

The impact of native competitors on an alien invasive: temporal niche shifts to avoid interspecific aggression?

Abstract: The American mink, Neovison vison, is an established, alien invasive species in the United Kingdom that originally colonized the country at a time when two native mustelids (otters, Lutra lutra, and polecats, Mustela putorius) were largely absent. Both of these species are now recovering their populations nationally. We compared the relative abundance and the behavior of mink in the 1990s and in the 2000s in an area of southern England where both otters and polecats were absent in the 1990s but reappeared in the intervening years. We found that mink were still abundant in the 2000s in the presence of otters and polecats, but that they appeared to have altered some aspects of their behavior. In accordance with previous studies, we found that mink consumed fewer fish in the presence of otters. We also found that mink were predominantly nocturnal in the 1990s (in the absence of competitors) but were predominantly diurnal in the 2000s (in the presence of competitors). We hypothesize that this temporal shift may be an avoidance mechanism allowing the coexistence of mink with the otter and the polecat, although we are unable to attribute the shift to one or the other species. We also found that mink in the presence of competitors weighed less but remained the same size, suggesting the possibility of a competitor-mediated decline in overall body condition. This is one of very few field studies demonstrating a complete temporal shift in apparent response to competitors. The implications of this study are that recovering otter populations may not lead to significant and long-term reductions in the number of invasive mink in the United Kingdom as has been suggested in the media, although we cannot exclude the possibility of a decline in mink in the longer-term.