Extreme heat and drought are putting new pressures on wildlife in Arizona, even species that have adapted to desert conditions over thousands of years.

A biologist who studies rattlesnakes had never seen one of the reptiles die in its underground burrow, until a record heat wave sent temperatures soaring.

Some species will try to move to cooler habitat, but they often face barriers, such as highways, border walls or mountaintops with nowhere to go.

For almost 25 years, Mike Cardwell has been studying rattlesnakes in the desert using radiotelemetry devices. With surgically implanted transmitters inside the snakes, he can track both their location and their internal temperature in the wild.

Before 2023, the hottest internal temperature Cardwell ever recorded in a living snake was around

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