Meeting Abstract
Recent heat waves have led to mortality of animals across the globe including humans, which has drawn new attention to how animals cope with thermal stress. Currently, there is a strong focus on characterizing physiological lethal limits of thermal stress in endotherms to predict how heat waves in a changing climate will affect populations. Less well studied are the sublethal effects of thermal stress on animal behavior, which may influence both survival and reproductive success. Here we show that birds (zebra finches) exhibit reduced cognitive and motor performance on foraging tasks when exposed to naturally occurring high temperatures. First, birds showed poorer inhibitory control in a detour-reaching task at high temperatures, indicating that heat can limit cognitive performance. Second, birds were less efficient at foraging in a color-association task at high temperatures, despite high accuracy in associating food with colors, providing further evidence that high temperatures limit cognitive performance and that cognitive functions vary in their susceptibility to limitation by heat stress. Third, birds performed the timed color-association task more slowly at high temperatures because they stopped to perform thermoregulatory behaviors and because of slower muscle movement, indicating that heat limits motor performance. We anticipate that these findings will stimulate new research and planning objectives for climate change. These results provide a mechanistic link between the physiology of thermal stress to recently observed phenomena at the population-level, including range shifts and breeding failure. Further, these results expand our understanding of animal cognitive conditions during thermal stress, and will be of interest to those involved in animal production and welfare, human health, and human workforce planning.
