The surrounding photos are representative of the 54 species photos contained in this guide. All larger mammals of the greater Rocky Mountains are included as well as the most commonly seen representatives of the smaller species (chipmunks, ground squirrels, rats, voles, etc.). Photo size varies roughly in proportion to mammal size. Organization is by family; all rabbit pictures are adjacent to one another as are the squirrels, ungulates, weasels, etc.

Under the common name, measurements are listed which allow the user to compare relative mammal size. The legend used is as follows: L(hb)-length of head and body; L(t)-overall length from head to tail; Ht-height to shoulders; Wt-average weight range of animal. Length and height are in inches and weight is in pounds unless noted otherwise.

All three inside pages contain text blocks corresponding to each species pictured on the front. These provide common and scientific name, identification aids, behavior traits and often something of the species' role in nature.

Light brown above, darker below (especially on legs) with a buffy colored bib. Has large cat-like ears. Inhabits coniferous forests in cold climates. Extremely quick and agile tree climber where it spends much of its time. Somewhat secretive and shy. Inhabits wilderness areas with high squirrel and chipmunk populations, its main prey. Kills in typical weasel fashion with bite to back of neck. Also eats carrion, fruits and nuts.. Usually solitary. Active day and night throughout year. Avoids swamps and marshes. Trapping and lumbering have eliminated them from much of their former range.

Common tree squirrel of colder climates. Scolds intruders with long series of chattering. Active at dawn and late afternoon. Varied diet even includes mushrooms poisonous to humans. Stores food for winter use. These caches are important to bears who raid them. Does not hibernate but in severe winters builds underground snow tunnels. Only 25% survive their first year. Lives 2-3 years.