White-tailed deer (Odocoileus virginianus) can sometimes be seen on the trails of Fort St. Joseph. They are easily identified by their triangular brown tails which, when held upright at any sign of danger, show a white underside (the flag). Although they tend to be more wary of humans than other members of the deer family, white-tailed deer have been expanding their range in many places in North America as they adapt to human-caused changes in the environment.