Least chipmunk, Kootenai National Forest, Montana, United States

In the world of woodland critters, the least chipmunk might seem like the 'under squirrel'—but don't count it out.

With survival smarts and turbo-charged feet, this tiny rodent proves that being 'least' is no reason to squirrel away your potential.

Weighing less than a deck of cards and measuring under 25 centimetres from nose to tail, this species is North America's smallest chipmunk.