In Depth: For Wildlife That Survives the Heat, the Cost Often Comes Later

The monkeys fell from the trees like ripe fruit, hitting the ground with a thud.

In May 2024, summer had come early and hard to the state of Chiapas in southern Mexico. In an ordinary year the temperature in the jungle would have topped out around 32 degrees Celsius. At the time, it was pushing 45 C.

The jungle had turned hot and dry. In the canopy, an endangered species of primate called howler monkeys — named for a call that can carry more than a mile — began to succumb to the heat. The temperature had climbed past what their bodies could bear. The monkeys grew dehydrated, then limp, until they could no longer hold on and fell, one after another, from the branches.