Characterization of woodchuck burrows within seven sensitive areas at Antietam National Battlefield,Maryland

The goal of a two-year study of the woodchuck (Marmota monax) on Antietam National Battlefield (ANTI) in Maryland was to reduce continuing damage to the Park's unique cultural and historical resources caused by woodchuck burrowing and scent-marking behavior. Park managers were concerned with increased maintenance costs, loss of biological and historic resources, and visitor safety as a result of the high density woodchuck population. Data were collected on all burrow systems found within seven sensitive areas, defined as historical farmsteads and high visitor usage areas, within ANTI. Burrow activity status (active, inactive), number of entrances, presence of secure objects, distances to roads and walkways, and damage ratings were recorded for each system. Chewing and burrowing damage was assessed on its potential for the undermining of monuments, building foundations, rock walls and fences and its visibility to park visitors.Burrow systems (n = 115) were found at all sensitive area sites (range = 3–28) and burrows were significantly associated with secure objects (n = 81 with, n = 34 without; 2 = 19.38, P < .01). Cultural or historical objects had burrows associated with them more often than natural landscape features including rocks, trees or stumps (n = 62 cultural; n = 19 natural; 2 = 28.4, P < .01). The average distances of burrows to pedestrian traffic was 30.4 m across all sensitive areas. Chewing damage was found at six sensitive areas distributed nearly equally among woody vegetation, fences and buildings. Undermining of walls and buildings was more common than undermining of fences and monuments. Woodchuck burrowing damage was visible to the public at 33 (29%) of the burrow systems and the average damage rating was highest at the National Cemetery (1.8) and lowest at Burnside Bridge 1.1 (scale of one to three). The average damage rating for all sensitive areas was 1.4.Woodchucks may instinctively select secure objects for protection from predators. The animals' significant association with burrows in the sensitive areas makes secure objects an important contributing component of an area's suitability. An increase in maintenance and human activity combined with exclosure of woodchucks may reduce an area's suitability for woodchucks. Continued inventory and monitoring of areas of concern will be recommended as part of a pro-active management approach emphasizing habitat modification and suitability reduction based on our scientific findings.