This lifeform is generally found west of the Continental Divide in North America

Western terrestrial garter snake (Thamnophis elegans vagrans) is found from northern Arizona and northern New Mexico to southern British Columbia and southern Alberta. There are several subspecies. This complex is usually absent from the dry desert areas of Southern California, Arizona, and New Mexico. This is a smaller snake rarely exceeding three and one half feet in length.

Thamnophis genus (garter snakes) contains about thirty species of snakes native to Central and North America. About fourteen of these species can be found in North America. In many parts of North America the garter snakes are the most common and most easily observed snakes. Many have longitudinal yellow or pale stripes or lines along their entire body. Many species have a reddish tongue with a forked black tip.

Family Colubridae contains the vast majority (70% of all snakes) of the world's species of snakes. The number is estimated to be over 1,850 and possibly up to 2,500.

Lizards and Snakes (Squamata Order) share many common characteristics and consequently they are grouped in a single order. There are greater differences between some groups of lizards than there are between other groups of lizards and snakes. The same is true of snakes. Lizards and snakes share a common skull shape.

Reptiles (Class Reptilia) are an ancient group of scaled  chordates. These scales may be permanently joined, as in the  turtles, or flexible, as in the snakes. Reptiles are land-based. Their eggs are laid on land and the young are air breathing.

Backboned Animals (Phylum Chordata) are the most advanced group of animals on earth. These animals are characterized by having a spinal cord or backbone. Most members have a clearly defined brain that controls the organism through a spinal cord. Fish, amphibians, reptiles, birds, and mammals are in this phylum.

Currently, some taxonomists believe that the fish should be divided into two groups (sharks and regular fishes) and that there are some other primitive groups in the phylum such as hagfish or lampreys.

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.