Monocacy National Battlefield provides an excellent habitat for a wide variety of mammal species. A total of 34 different species have been known to inhabit the park. Most of the species that utilize the park’s resources are small, such as the short-tailed shrew, the woodland vole, the muskrat, the southern bog lemming, the meadow jumping mouse, and the hairy-tailed mole. Most of these small mammals are rarely seen because they live underground in small burrows.

Other small mammals such as eastern chipmunk and the gray squirrel are more commonly seen by visitors of the park. You may even be lucky enough to see the southern flying squirrel, which is the only nocturnal squirrel of its kind, and can retain flight for up to 80 yards.

There are also several medium-sized mammals found in the park, including the red fox, the raccoon, the striped skunk, and the groundhog. You may also see the mink, a semi aquatic carnivore whose tail constitutes 1/3 of its entire length and is an excellent swimmer.

The larger mammal species found in the park include black bear, white-tailed deer, and coyotes. While black bears are rarely spotted, and usually are only passing through, white-tailed deer are found in abundance. The rising population of deer has an intense affect on the herbaceous and woody plants found within the park. Several studies have been conducted on the effects of the overpopulation of deer in the park.