Intense Heat
Intense heat can measurably impact animal behavior, and much of that impact can be attributed to a muddling of brain function.
Animals become more aggressive and less likely to solve puzzles, even those that are necessary to acquire food, when it’s hot outside. Birds spend less time feeding their young and sing less, opting instead to sit still with their wings spread, panting through open beaks while trying to dissipate the heat.
The risk of being bitten by a dog is higher on hot, sunny days—10% higher on a 90-degree (F) day compared to a 60-degree day. Snakes and cats are also more likely to bite when it’s hot outside, and some types of goat-antelope become a lot more aggressive as the mercury rises.
An experiment that looked at a bird’s ability to learn at different temperatures found that zebra finches required twice as many trials to learn how to get food out of a simple puzzle box during simulated heat waves, and mice have trouble solving (even familiar) mazes when experiencing heat stress.
Similar issues have been shown in bumblebees, fish, and even desert species acclimated to hot weather; all of them suffering new limitations when overheated, especially in terms of learning and responding appropriately to external stimuli.
This is expected to become an even more pressing issue as global climate change contributes to bigger and more regular temperature swings, and as some areas become on-average hotter (with higher extremes) more of the time.