While many studies have detailed the complex intricacies of the endothermic immune system, relatively little is known about the immune system of ectotherms--specifically, reptiles. In an attempt to gain more knowledge about the factors affecting reptilian immune function, ornate box turtles (Terrapene ornata) were subjected to chronic stress in the form of high ambient temperatures in a semi-natural environment. It was hypothesized that chronic stress would lead to elevated levels of corticosterone in the blood, which would, in turn, suppress immune activity. It was found that body temperature and body mass in particular were significantly affected by chronic heat stress. Among turtles subjected to chronic heat stress, white blood cell to red blood cell ratios decreased and numbers of natural antibodies decreased--all of which suggests lowered immune activity. This decrease in immune activity correlated with increases in body temperature as well as body mass. Changes in corticosterone levels within and between both treatment groups were insignificant. Taken together, these results suggest that turtles subjected to chronic heat stress experienced improved health due to increased body mass, increased body temperature, and decreased immune function. This study reinforces the complexity of the stress response, and it highlights its far-reaching effects not only on immune function, but also on the body as a whole
