Hello again to all desert tortoise enthusiasts! It’s about that time of year for desert tortoises to begin their winter hibernation. For anyone who is new to the desert tortoise Gopherus aggaszzi, this is the time of the year when temperatures start to drop and food becomes scarce. With this seasonal change, desert tortoises begin to slow their metabolism and physical performance and search for a dark, comfortable burrow to “sleep in” through the winter until temperatures warm and food becomes more available.
Finding a secure, empty burrow in the Mojave Desert can be more difficult than just finding a hole in the ground. Desert tortoises search or create their own shelters: they may dig burrows, take another animal’s burrow, or find a small cave that protects them from the cool winters of the Mojave Desert. There are many other animals here that also are looking to hibernate or find shelter from the cold; they may cohabit a burrow with the desert tortoise through the winter season. Animals that have been known to share burrows with desert tortoises are black-tailed jackrabbits and desert cottontail rabbits as well as predators like kit foxes, coyotes, and even badgers.
Recently at the San Diego Zoo Desert Tortoise Conservation Center (DTCC), a new, reinforced fence was built to help control the movement of predacious animals onto the property. Prior to the new fence, coyotes, kit foxes, and even badgers would dig below the fence line to enter the property. This situation became a problem due to attacks on the desert tortoises and the destruction of the grounds at the DTCC. Once the new fence was built, there were no more issues with predacious animals entering, killing, or harming the tortoises.
Unfortunately, the DTCC now has a much larger problem with the local fauna. Since larger, predacious animals are not entering the property, nothing is controlling the population of smaller mammals such as rabbits and antelope ground squirrels. These animals do not directly harm the tortoises at the DTCC but harm them indirectly by scavenging the tortoises’ chow, grasses, and water we put out for the tortoises. It only shows that changing an animal’s ecosystem is not always the best answer to conserving that ecosystem.
Daniel Essary is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, Desert Tortoise: Hot, Hot, Hot.