On August 25, photographer Paul Donahue got a call: A large male jaguar had been spotted on the hunt in central Brazil's Tres Irmãos River.

Donahue, who tracks jaguar sightings for ecotourism operator Southwild in Mato Grosso (map), arrived at the scene to find an animal named Mick Jaguar hidden in thick grass, stalking a nearby group of caiman, a crocodile relative native to South America (pictured).

"Over the next 30 to 40 minutes we watched the jaguar very slowly slink along in the direction of the yacaré," he wrote in his field notes. (Read "Path of the Jaguars" in National Geographic magazine.)

The largest of South America's cats, jaguars are good swimmers and regularly prey on fish, turtles, and caimans. They also eat larger animals such as deer, peccaries, capybaras, and tapirs.

—Christine Dell'Amore