Least Weasel

Mustela nivalis

The least weasel is classified as the world's smallest carnivore. As with other weasels, it is typically described as being curious, alert and bold - actively investigating every hole and nook they encounter during their hunting rounds in search of small rodent prey. Currently, the least weasel enjoys a circumboreal distribution throughout the Holarctic, and in North America it is found throughout Alaska and Canada and southward to the U.S. Great Lakes and midwestern states. During the late Pleistocene, their range extended further south into Missouri, Kentucky and Tennessee. 

Least Weasel

Least Weasel (Mustela nivalis) at the British Wildlife Centre, Surrey, England - photograph taken Sunday 17. August 2008. By Keven Law (originally posted to Flickr as On the lookout...) [CC-BY-SA-2.0 (www.creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Carnivora (Dogs, Cats, Bears, etc.)
Mustelidae (Weasels)

Length: males 13-26 cm (5.1-10.2 in) body, 1-9 cm (0.4-3.5 in) tail; females 11-20 cm (4.3-7.9  in) body, 2-6 cm (0.8-2.4 in) tail

Weight: males 36-250 g (1.3-8.8 oz); females 30-117 (1.1-4.1 oz)