As we begin the new year at the San Diego Zoo Desert Tortoise Conservation Center (DTCC), almost all the tortoises have gone down into their burrows for their winter brumation (reptilian hibernation). During the winter months, we shift our responsibilities from feeding and processing tortoises (giving health assessments to those brought in to the DTCC) to doing surveillance in our assigned areas. We walk each section of pens looking for sick or injured tortoises and for damage that needs to be repaired in the pens.
At this time of year, with consistently cool weather, all the tortoises should be pretty well entrenched in their burrows. After we are comfortable that the tortoises are down for the winter, we create a wall of earth in the opening of each burrow to provide an extra layer of protection against the elements. At this point, any tortoise found outside of their burrow is cause for concern. When we find tortoises out in cool weather, we bring them in for a complete health assessment.
All sick or injured tortoises are kept in the medical center for treatment, and the tortoises that appear healthy are put back in their pen and checked more frequently to monitor any change in their condition. Typically, tortoises that are awake and out of a burrow during the cold winter months usually have a health issue causing them to come out of brumation. Doing pen surveillance is the only way we can monitor the condition of the tortoises during the winter. Since it is not healthy to disturb the tortoises in their burrows, we have to closely monitor the behavior and condition of the tortoises that are active outside their burrows.
Rachel Foster is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Saving Tortoises, One Urolith at a Time.