INVENTORY OF MAMMALS (EXCLUDING BATS) OF GEORGE WASHINGTON BIRTHPLACE NATIONAL MONUMENT

Natural Resource Technical Report NPS/NCBN/NRTR—2010/311

Ronald E. Barry
Bates College
Biology Department
409 Carnegie Science Hall
44 Campus Avenue
Lewiston, Maine 04240

Tressa L. Dolbeare
Department of Biology
201 Compton Science Center
Frostburg State University
101 Braddock Road
Frostburg, Maryland 21532-2303

April 2010

U.S. Department of the Interior
National Park Service
Natural Resource Program Center
Fort Collins, Colorado

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Abstract

A survey of mammals (bats excluded) at George Washington Birthplace National Monument (GEWA) was conducted from 2002 to 2003 to document the presence of > 90% of the mammals in the park, describe their distributions and relative abundances, quantify habitat-specific species diversity, and provide recommendations for management and conservation. Surveys relied on live trapping with Sherman and Tomahawk traps for small to medium-size mammals, the use of pitfall traps to capture small shrews, direct observation of individuals and their sign (tracks, scats), and remote photography. We identified five principal habitats – grassland (fields), mixed deciduous-coniferous forest, pine plantations, logged areas (of mixed forest), and wetlands – and several less expansive habitats, and targeted locations for sampling.

Twenty-one species of mammals were either captured or observed within GEWA, resulting in six new records (species) for the park. Altogether, six orders and 12 families of mammals are represented by these species. Including the new records, we documented 70% (21 of 30) of the species (excluding bats) predicted to occur and 75% (15 of 20) of those for which historical records exist. New species we recorded include the American least shrew (Cryptotis parva), southeastern shrew (Sorex longirostris), eastern harvest mouse (Reithrodontomys humulis), red fox (Vulpes vulpes), North American river otter (Lontra canadensis), and long-tailed weasel (Mustela frenata). The white-footed deermouse (Peromyscus leucopus) occupied all of the principal habitats and was the most abundant mammal in the park. Multiple individuals of two grassland specialists, the seldom captured least shrew and spottily distributed eastern harvest mouse, were captured. Also of note, river otters (or their sign) were observed in two locations, on the beach along the Potomac River and along the park’s eastern boundary at Popes Creek. Grasslands exhibited the greatest species diversity of small mammals, and logged areas exhibited the least diversity.

The park supports a predictable assemblage of mammals given the diversity of habitats present. Habitat generalists, such as the white-footed deermouse, northern short-tailed shrew (Blarina brevicauda), Virginia opossum (Didielphis virginiana), raccoon (Procyon lotor), and whitetailed deer (Odocoileus virginianus), are widely distributed. Adequate quality and quantity of habitat exist to sustain populations of grassland specialists such as the least shrew, eastern harvest mouse, and meadow vole (Microtus pennsylvanicus).

Additional inventory and monitoring work should be conducted to determine the status of a number of species either detected in low numbers – the southeastern shrew, marsh oryzomys or rice rat (Oryzomys palustris), southern flying squirrel (Glaucomys volans), long-tailed weasel – or not confirmed but for which previous records exist – woodland vole (Microtus pinetorum), muskrat (Ondatra zibethicus), house mouse (Mus musculus), brown rat (Rattus norvegicus), and mink (Neovison vison). This work would necessarily include additional sampling of wetlands and grasslands. A concerted effort should be directed toward documenting the populations of small shrews (Sorex spp.) in the park with greater use of pitfall traps (only after proper archeological compliance or oversight has been completed). In addition, the following resource management strategies might be considered, continued, or enhanced: 1) affording special consideration for the protection and conservation of wetlands that support a number of mammal species in GEWA; 2) regulating visitor use of specific areas where sensitive wetland species (e.g, the river otter) are found; 3) maintaining diverse herbaceous communities and interrupting succession in managed fields by careful attention to mowing and burning schedules; 4) acquiring adjoining agricultural land so that it can be managed for native vegetation and mammal species (and reduction in populations of the exotic house mouse); 5) periodically monitoring for exotic house mouse, brown rat, and black rat (Rattus rattus) populations; 6) using management practices (e.g., fumigants or live trapping and relocation) to control groundhog (Marmota monax) populations; 7) using management practices (e.g., live trapping and relocation) to eliminate problematic mammalian predators such as foxes and weasels that prey on GEWA farm fowl; 8) using management practices that either reduce the raccoon population or the consequences of human activities that sustain it (e.g., more frequent monitoring of picnic areas and trash removal); and 9) monitoring and, if necessary, using management practices to regulate the white-tailed deer population to ensure the preservation of vegetation communities and understory cover important to mammals and birds. Raccoon and white-tailed deer populations, particularly because of rabies and Lyme disease (and abundance of the black-legged [deer] tick larvae and nymph reservoir-competent host, the white-footed deermouse), also are of potential public health significance in a historical park with high human visitation like GEWA.

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