Reptiles are ectothermic animals whose welfare is profoundly influenced by thermal environment, with many captive reptiles suffering chronic welfare compromise from inadequate temperature gradients.
Reptile welfare in zoo and captive settings is fundamentally a thermal welfare issue, because thermoregulation is the central behavioural priority for ectothermic animals. In the wild, reptiles spend significant portions of their active day selecting microhabitats that allow them to achieve and maintain body temperatures optimal for digestion, immune function, reproduction, and cognitive performance. Captive exhibits that provide only narrow temperature ranges, or that have inadequate thermal gradients, prevent this essential behavioural thermoregulation. The welfare consequences are systemic: suboptimal body temperatures impair digestion (leading to nutritional deficits even when food is adequate), suppress immune function (increasing disease susceptibility), and may cause chronic discomfort analogous to persistent cold or heat. The addition of precise thermal monitoring and multiple independently controlled thermal zones to reptile exhibits has transformed welfare outcomes in well-resourced zoos. UV-B provision is equally important: without appropriate UV-B for vitamin D synthesis, reptiles develop metabolic bone disease - a condition causing bone weakness, deformity, and chronic pain that is entirely preventable. Reptile welfare requires species-specific knowledge that many general zoo keepers may lack.