Photo: Jessica Starkey

White-tailed deer can be seen in several areas of the park.

The park is home to more than 30 mammal species. Some of these, however, such as the American mink (Mustela vison) and the short-tailed shrew (Blarina brevicauda) are not frequently observed. Hiking the Appalachian Trail up Loudoun Heights, gray and fox squirrels (Sciurus carolinensis and S. niger) can be viewed scurrying to stash their food, while eastern chipmunks (Tamias striatus) are commonly seen running right along the trail's edge. In a 2001 mammal survey, the southern flying squirrel (Glaucomys volans) was found to be making its home within the park.

During the early morning hours, white-tailed deer (Odocoileus virginianus) can be found browsing on understory vegetation as hikers make their way to the MarylandHeights overlook. Throughout the day, groundhogs (Marmota monax) often peek up from vegetation along almost any roadside within the park, while after dark, Virginia opossums (Didelphis virginianus) and raccoons (Procyon lotor) are more likely to be encountered in these areas.