The jaguar is a compact and well-muscled animal. Larger males have been recorded as weighing 159 kilograms and smaller ones have extremely low weights of 36 kilograms. Further variations in size have been observed across regions and habitats, with size tending to increase from the north to south.
The jaguar has been attested in the fossil record for two million years and it has been an American cat since crossing the Bering Land Bridge during the Pleistocene; the immediate ancestor of modern animals is Panthera onca augusta, which was larger than the contemporary cat. Its present range extends from Mexico, through Central America and into South America, including much of Amazonian Brazil. The countries included in this range are Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname and Venezuela. The jaguar is now extinct in El Salvador and Uruguay.
The jaguar can range across a variety of forested and open habitat, but is strongly associated with presence of water. Forest jaguars are frequently darker and considerably smaller than those found in open areas, possibly due to the fewer large herbivorous prey in forest areas. A short and stocky limb structure makes the jaguar adept at climbing, crawling and swimming. The base coat of the jaguar is generally a tawny yellow, but can range to reddish-brown and black. The spots vary over individual coats and between individual Jaguars: rosettes may include one or several dots, and the shape of the dots varies. The jaguar closely resembles the leopard, but is sturdier and heavier, and the two animals can be distinguished by their rosettes: the rosettes on a jaguar's coat are larger, fewer in number, usually darker, and have thicker lines and small spots in the middle that the leopard lacks. Jaguars also have rounder heads and shorter, stockier limbs compared to leopards.
Jaguar females reach sexual maturity at about two years of age, and males at three or four. Mating fights between males occur, but are rare, and aggression avoidance behaviour has been observed in the wild. Mating pairs separate after the act, and females provide all parenting. The young are born blind, gaining sight after two weeks. Cubs are weaned at three months but remain in the birth den for six months before leaving to accompany their mother on hunts.
Typical lifespan in the wild is estimated at around 12–15 years; in captivity, the jaguar lives up to 23 years, placing it among the longest-lived cats. Like most cats, the jaguar is solitary outside mother-cub groups. Adults generally meet only to court and mate though limited non-courting socialization has been observed anecdotally and carve out large territories for themselves. Female territories, from 25 to 40 square kilometers in size, may overlap, but the animals generally avoid one another. Male ranges cover roughly twice as much area, varying in size with the availability of game and space, and do not overlap. Scrape marks, urine, and feces are used to mark territory. Both sexes hunt, but males travel farther each day than females, befitting their larger territories. Like all cats, the jaguar is an obligate carnivore, feeding only on meat.
The jaguar is a stalk-and-ambush rather than a chase predator. The cat will walk slowly down forest paths, listening for and stalking prey before rushing or ambushing. The jaguar attacks from cover and usually from a target's blind spot with a quick pounce; the species' ambushing abilities are considered nearly peerless in the animal kingdom by both indigenous people and field researchers, and are probably a product of its role as an apex predator in several different environments. The ambush may include leaping into water after prey, as a jaguar is quite capable of carrying a large kill while swimming; its strength is such that carcasses as large as a heifer can be hauled up a tree to avoid flood levels.
Jaguars are listed on the endangered species list. It is estimates that there are only about 15,000 jaguars left in world. As the forest disappears, the jaguars that are left, are forced to seek new homes and usually migrate north in search of the lust jungles and forests. Jaguars are also the target of many hunters because their skins are sold for a lot of money to make clothes, purses and other things.