For animals such as fish and insects that cannot regulate their body temperature, heat waves can be particularly harmful. “Changes in air temperature will affect brain temperature,” says Baird. A hotter brain can inhibit nerve activity, which can “affect sensation, memory and learning,” he says.
Cross-section shows a band of cells in the mouse hippocampus.
Credit: RAUNAK BASU / UNIVERSITY OF UTAH, SALT LAKE CITY
Cross-section shows a band of cells in the mouse hippocampus.
Credit: RAUNAK BASU / UNIVERSITY OF UTAH, SALT LAKE CITY
When Baird et al tried to teach honeybees to associate the sweet sucrose with the color blue and yellow and bitter quinine, most bees learned the trick at 77°, but less than half did it at 90°. Such poor cognition can cause problems in the field: If insects forget which flowers to pollinate (in the case of bumblebees, these include tomatoes and blueberries) or how to get home with nectar, not only pollinators sufferbut so does human agriculture, says Baird.
The heat also dangerously reduces the vigilance of animals. In Ridley’s recent experiments, the mercury once reached 96° F in the Kalahari desert. pied babblers have lost the ability to respond appropriately to predators. During the studies, the researchers lured the birds to a mysterious shape covered with a sandy-colored blanket, using worms as bait. As soon as a rumormonger approached, the scientists would reveal what was hiding underneath: either a taxidermied cat-like carnivore called a genet, or a wooden box of the same size and color. The birds were genetically frightened by the cool temperatures – they would call, scan their surroundings or simply run away. But when it was hot, they behaved the same way whether they were facing the carnivore or the box. Ridley suggests that this could translate into a higher chance of fatal predator attacks as the heat rises, which could hurt populations of gophers and other predatory species.
These studies are not mere abstractions. Temperatures are rising in the Kalahari, where southern hunters use it to search for worms. twice as fast as the global average. In tropical rivers, male guppies search for their mates. heat waves grow longer and more intense. It’s the same story across much of the planet—temperatures are rising and animal thinking is straining, potentially putting species at risk. Effects can be increased in certain areas like citiesoften exhibit warmer temperatures than non-urban areas. “We probably underestimate the effects of rising temperatures on animal minds,” says Ridley.
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