The jaguar is the largest cat native to the western hemisphere. A large male can reach 100 kg (220 lb.), and females are about 25% lighter.

Jaguar coats are patterned by rosettes of 4 or 5 dark markings arranged around a central light area, often with dark spots inside. Their relatively heavy, stocky bodies (compared to leopards, for example) prevent jaguars from being good climbers. They are, however, good swimmers.

Inhabiting thick, wooded country and arid, shrubby areas, jaguars often make their dens in caves or under overhanging rocks. A typical litter consists of 1 to 4 young, born about 100 days after mating.

The natural prey of this carnivore includes a large variety of animals of tropical South America. The more important of these are capybaras, peccaries, turtles, tapirs, deer and alligators.

Commercial exploitation for skins is no longer a significant threat to their survival, despite the fact that law enforcement in some areas is difficult. More serious threats are loss of habitat and death at the hands of cattle ranchers. Its range once extended from the southern United States through Mexico, Central and South America east of the Andes to Argentina. Jaguars have been extirpated from the dry northern portions of its range and have been reduced in numbers in most but the central portions. The rainforest of the Amazon River drainage basin is the key stronghold of this species.