Because gray squirrels do not begin gnawing on bone until the flesh and fat is gone (they gnaw the bones for calcium and minerals), the presence of gray-squirrel gnaw marks on bone, can assist in making a minimal estimate of the time-since-death in a temperate environment similar to that of East Tennessee. The experiment found that whereas the brown rat will scavenge bone to obtain nutrients (for example, fats), the native eastern gray squirrel gnaws bone to acquire minerals (for example, calcium phosphate) after fats are gone from the bone. These different motives for gnawing bone result in patterned differences in the location and timing of bone use by the two species. Brown rats attack bones at location with minimal cortical thickness for easy access to fat-laden bones. Gray squirrels, on the other hand, generally gnaw near the edge of bone where cortices are thick. The postmortem interval for gray squirrel gnawing on the remains located in a shaded portion of the Tennessee ARF was slightly over 30 months. The ARF is a semiwooded area set aside for human decomposition research and skeletal processing for the William M. Bass Donated Skeletal Collection. At any time during the research (fall 2003-fall 2006) approximately 50-75 bodies were in various decomposition stages on the ground's surface. Remains were generally collected within 16 months after being placed in ARF. Digital photographing focused on areas of scavenging activity in both daytime and nighttime hours. 1 table, 8 figures, and 55 references