49 mammalian species, aside from humans, are known to occur within Pinnacles National park. Those often seen and enjoyed by visitors and staff include: black-tailed deer, bobcat, gray fox, raccoon, jackrabbit, brush rabbit, ground squirrel, chipmunk, and several kinds of bat. These animals are reported regularly because they are either easy to see or charismatic. Badgers, coyotes, a wide variety of rodents, and mountain lions inhabit the park, but are not commonly seen. The infrequent sighting of some of the mammals in the park points to a difficulty in studying them: extensive monitoring is required to determine baseline data on all mammalian species within Pinnacles. This work will be ongoing for many years, and we will keep you informed about it. For example, we are currently conducting a small mammal survey, which may soon be available on our web pages. The mammals at Pinnacles belong to the following orders: Marsupialia (1), Insectivora (3), Chiroptera (16), Lagomorpha (3), Rodentia (15),Carnivora (9) and Artiodactyla (2). Included in these are three mammals which have been introduced to Pinnacles -- the house mouse, opossum, and feral pig. The house mouse (Mus musculu s) and opossum (Didelphis virginian a) are rare and not considered threatening to Pinnacles' native ecosystems. Feral pigs (Sus scrof a), on the other hand, are abundant within the park and cause extensive damage to the native vegetation. Based on several years of research, a decision was made to construct a fence around the park's perimeter. Pigs within the fence will be removed, and new pig incursions will be prevented.