Long-tailed Weasel (Mustela frenata) is the most widely distributed mustelid in the New World. Its range extends from southern Canada through most of the United States to Mexico, Central America and the northern parts of South America. It is generally found in open or semi-open habitats near water.

This is a typical weasel with a long slender body, short legs and a bushy tail that is almost as long as the rest of the animal. Adult males measure from 33 to 45 cm (including their tails), and may weigh up to 450g; females are typically about 15% smaller. They are gingerish-brown in colour, with yellowish-white belly fur, but in the northern parts of their range they moult to pure white in winter. The tip of the tail is black in all seasons.