The animal life at Bent's Old Fort is typical of both semi-desert prairie and riparian habitat. To date ninety-nine species of birds, twenty species of mammals, and ten species of reptiles and amphibians have been identified at the site. 

The most commonly seen animals at Bent's Old Fort include White-tailed deer, Mule deer, Coyote, Wild turkey, Desert cottontail, Western rattlesnake and a variety of birds.