Advances in New Zealand mammalogy 1990–2000: Stoat and weasel

Abstract

C. M. King*, K. Griffiths*, E. C. Murphy**27. STOATMustela erminea Linnaeus, 1758For a searchable database of stoat references, see King, CM. (2000) Stoat bibliography,[online] Available: http://www.invasive-mammals.org.nz/stoats/ [retrieved Insert Date ofRetrieval].DescriptionAfter combining several phylogenetic analyses, Bininda-Edmonds (1999) reached theconclusion that the stoat is most closely related to the mountain weasel M. altaica, but is alsovery close to the common weasel (M. nivalis) and the long-tailed weasel (M. frenata). Thenext closest relatives are New World species, the Colombian weasel M. felipei and thetropical weasel M. africana, both previously considered to be part of the sub-genusGrammogale.The change to a white winter coat, typical of stoats living where winters are predictablycold, is controlled both by genetic and by environmental factors (Feder 1990). Stoats are welladapted to climates much colder than New Zealand, and were among a handful of species tosurvive in Britain throughout the last (Devensian) glaciation (Yalden 1999).Body fat is deposited at several sites in succession, first along the spine and kidneys, thenon gut mesenteries, in cavities under limbs, and finally around shoulders. Even very fat stoatsthereby retain their tubular shape (King 1989b).In Nearctic populations, long-term geographic variation in size is correlated with climaticvariables, but variation in shape is more likely to be related to the history of recolonisation ofnorthern lands from different glacial refugia (Eger 1990). In the Palaearctic, geographicalvariation in size is more complex and apparently related to the distribution of prey sizes(Erlinge 1987; Meia & Mermod 1992). In New Zealand, there is significant short-termvariation in size, due to nutritional conditions during the period from implantation toindependence (Powell & King 1997). Growth of young stoats born in beech forest populationsafter a good seed year, when mice are abundant, is temporarily enhanced. In large samplesfrom Fiordland and Craigieburn collected in the 1970s, the difference was detectable in skulllength, which is fixed early, but not in body weight, which is changeable throughout life.