Infrared thermography (IRT) is a tool that can be used to estimate temperature remotely by measuring the amount of thermal energy that an animal or object emits. All living organisms emit thermal energy in the form of radiation as a result of normal physiological processes. An IRT camera can be used to create a visual map of an animal’s body temperature, which can potentially be applied to measuring changes in blood flow associated with animal emotions. Developing new ways to non-invasively measure animal emotions can help us better understand their welfare. We collected IRT images of western lowland gorillas (Gorilla gorilla gorilla) to measure their responses to interactions with humans during routine husbandry and training exercises. We compared thermal changes to observations of their behavior and concentrations of two salivary hormones: oxytocin, which is associated with social bonding, and cortisol, which can indicate a stress response. Hormone levels did not change during these interactions, but we did see significant differences in temperature indicating that the gorillas showed higher arousal following human interaction compared to a control condition. Developing innovative techniques like IRT are essential to the mission of the Center for Zoo and Aquarium Animal Welfare and Ethics, because they give us more tools to ensure that animals are thriving at the Zoo.

https://doi.org/10.3390/ani9090604