Several dozen mammals inhabit the park on a permanent or intermittent basis. Fox, ground-hogs, raccoons and numerous rodent species are resident. White-tail deer travel through the park as they move up and down the forested areas along Wolf Trap Creek, Old Courthouse Creek and Difficult Run. Beaver have intermittently resided along Wolf Trap Creek. The first systematic study of park mammals is currently on-going.
The diversity of park ecosystems allows many other animal groups to live alongside these mammals. Multiple acres of wetland as well as a two-acre pond are conductive to reptile and amphibians, while native meadows (such as the one recently restored in the area known as the "Dimple," located in front of the Filene Center's main gate) provide habitat for bees, wasps, butterflies, moths, and birds. Surveys to systematically study and document these species are currently on-going.