Southeastern Pocket Gopher (Geomys pinetis) Tunnels Provide Stable Thermal Refugia

Animals living underground deal with multiple physiological challenges, such as hypoxia and hypercarbia, but may have reduced thermoregulation demands because of the more stable underground microclimate. Southeastern pocket gophers (Geomys pinetis Rafinesque) occur in the fire-adapted, open-pine forests of the southeastern Atlantic Coastal Plain where prescribed fire is commonly used to manage understory vegetation. They are almost exclusively fossorial, and their tunnels provide ecological services, including shelter, for a suite of commensal vertebrates and invertebrates. To quantify potential thermoregulation benefits of southeastern pocket gopher tunnels, we compared temperatures in active tunnels (n = 31) to aboveground temperatures during winter (December 2018-February 2019), and to aboveground temperatures during prescribed fire events (n = 16) occurring in spring (March-May 2019). During winter, tunnels provided a more stable thermal environment (average range = 6.5 +/- 0.8 C; mean +/- SE) relative to aboveground (average range = 24.8 +/- 1.8 C) temperatures. Similarly, mean tunnel temperature range (2.05 +/- 0.5 C) was significantly narrower than aboveground temperature range associated with fire events (497.0 +/- 101.4 C). Clearly, tunnels provide a stable thermal environment for pocket gophers and commensals that use their tunnel systems.