The jaguar is the only living representative of the genus Panthera occurring in the Americas and is known as one species over its entire range. Previously, eight subspecies of jaguars were described but more recent genetic and morphological analyses suggest four incompletely isolated phylogeographic groups: Mexico and Guatemala, southern Central America, northern South America north of the Amazon River and South America south of the Amazon River. Therefore, the jaguar is recognised as a monotypic species. 

The jaguar is the largest felid in the Americas. It is of stocky build with an unusually large head and relatively short legs. Compared to other big cat species, the jaguar has a distinctively powerful jaw. At first sight, the coat of the jaguar resembles that of the leopard but the pattern is different: the jaguar has larger, broken-edged rosettes around one or more small black spots. The base colour of its coat is pale yellow or tawny; its white belly, throat and inside of the limbs are marked with irregular black spots. The jaguar’s tail is relatively short in relation to its head-body length, spotted, and has from the midpoint to the tip several black rings. Melanistic individuals have been recorded. Moreover, also albinistic jaguars have been reported and it was even once intended to base a subspecies on an apparently albinistic colour morph from Paraguay. Jaguar body size varies across their range. The smallest jaguars occur in the Amazon and Central and North America, while the largest individuals can be found in the Pantanal and in the Venezuelan Llanos. These size differences are probably related to available prey base and the opened type of habitats.      

Black jaguars are called onça-preta, onça negra, pantera negra, yaguara, pichuna and yagua-hu.

The jaguar is listed as Near Threatened in the IUCN/SSC Red List of Threatened Species. However, its status varies regionally. The largest jaguar subpopulation is found in Amazonia and estimated at 57'000-64'000 individuals (89% of the total population). Out of 34 identified jaguar subpopulations, the one in Amazonia is the only one which is classified as Least Conern. All the other jaguar subpopulations are classified as Endangered or Critically Endangered. 

Of urgent conservation concern are the jaguar populations in the Atlantic Forest of Brazil, in the Cerrado of Brazil, in parts of the Chaco, northern Argentina, and in the Gran Sabana of northern Brazil, Venezuela and Guyana, as well as in parts of the coastal dry forest in Venezuela and in parts of Central America and Mexico. All these populations are assessed to have a low chance of survival. In the Atlantic Forest, the population is estimated to number only 200+/- 80 adults.

The jaguar has almost been eliminated from Mexico and the pampas scrub grasslands of Argentina, and has been extirpated from Uruguay and El Salvador. In the U.S. only dispersers and wandering individuals remain. These are observed in the south-western States and usually come from Northern Mexico. 

Population declines and habitat loss are recorded in most of its range countries. Connectivity between jaguar populations is lost and populations get more and more fragmented, particularly in eastern and southern Brazil, northern Venezuela and parts of Mexico and Guatemala. Isolated and small populations are more vulnerable to extinction. 

Estimating jaguar density is difficult because they are wide-ranging and elusive; estimates range from 1 to 11.7 adults per 100 km².

The geographic range of the jaguar reaches from southern Arizona through Mexico, Central America and South America, including the Amazon Basin, down to northern Argentina to the Rio Negro. Historically it also occurred in south-western U.S. (New Mexico and Texas). Today, the jaguar occupies only 51% of its historic range. 

The jaguar is adaptable, occupying a range of environmental conditions. It inhabits tropical forests, swampy grasslands, evergreen forests, pampas grasslands, wet savannas (such as the Pantanal) and mangrove swamps. The jaguar also occurs in conifer forests, deciduous broadleaf and mixed forests and in more arid environments such as dry deciduous forests and the thorn scrub woodlands of the Chaco. Generally, the jaguar is found at elevations below 1,000 m, but has been reported as high as 3,800 m. The jaguar does not occur in the high plateau of central Mexico or in the Andes above 2,700 m. The jaguar is often associated with water and avoids open or highly disturbed areas. It uses rocky caves or dense thickets for den sites.

The jaguar is a solitary, territorial predator and primarily nocturnal. However, the jaguar can also be active during the day. It is an excellent swimmer and can cross wide streams and readily catch fish, capybaras and caimans in the water and is thought to attract fish with its tail. The jaguar is the only big cat which regularly kills prey by piercing the skull with its canines. It has a massive head and robust canines which may be an adaptation to “cracking open” well-armoured reptilian prey such as land tortoises and river turtles. Prey is killed by jumping on them from the back or side and immediately biting in nape, the base of the skull or puncturing the brain case. Jaguars sometimes also kill large prey by making them fall by grabbing their head and breaking their neck through the fall. Smaller prey may be killed by a blow to the head.

The jaguar territories are marked with urine and faeces. Reported home ranges vary from around 10 km² for females in lowland tropical secondary forest of Belize to over 1,000 km² in the Yucatan Peninsula in Mexico. The smallest home ranges were found in Belize and Bolivia and the largest ones in Brazil and Mexico. Home range size is thought to be influenced by prey availability and abundance, habitat, environmental characteristics, human development and territorial disputes, and may vary seasonally.

Generally, males have larger home ranges than females, and often overlap with several females. Range overlap between individuals of the same sex (male-male and female-female) has frequently been detected but temporal avoidance is common.

Jaguars coexist with pumas (Puma concolor) throughout their geographic range. Studies have shown that even though jaguars and pumas may overlap in space, they may avoid one another in time.

The reproductive season can occur throughout the whole year but may be seasonal in some areas e.g. Venezuela (Jan-April). Females attract males by olfactory or vocal signs. Males and females stay together for up to 4-5 weeks. Estrus lasts for 6-17 days, the estrus cycle from 22-64 days and the gestation lasts 90-113 days. The birth interval is 22-36 months. In the Brazilian Pantanal an interval of 14 months has been observed. Cubs open their eyes between 3-13 days and begin to follow their mother at 2-5 months. They are fully dependent on milk until 11 weeks old; but by 3-6 months their diet is exclusively carnivorous. The average age at independence is 2-3 years for females and 3-4 years for males. In the Pantanal a female became independent at the age of 14 months; hunting totally by itself. 

The jaguar is included in Appendix I of CITES and fully protected over much of its range. Hunting is prohibited in Argentina, Brazil, Colombia, French Guiana, Honduras, Nicaragua, Panama, Paraguay, Suriname, the United States, Uruguay and Venezuela. In Belize, Costa Rica, Guatemala, Mexico and Peru hunting is restricted and in Bolivia trophy hunting is permitted. The jaguar is not legally protected in Ecuador and Guyana.

Jaguar Conservation Units (JCUs) are areas with a stable prey community, currently known or believed to contain a population of jaguars large enough to be potentially self-sustaining over the next 100 years; or areas containing fewer jaguars but with adequate habitat and a stable, diverse prey base, such that jaguar populations in the area could increase if threats were alleviated. Seventy-three JCUs have been identified from Mexico to Argentina.

The organisation Panthera has established a range wide “Jaguar Corridor Initiative” to link JCUs via corridors to ensure genetic exchange from north to south over the entire jaguar range. The key activities of the Jaguar Corridor Initiative involve:

• capacity building and the formation of national jaguar teams in each range country;
• ground truthing to identify the corridors; development and implementation of corridor action plans;
• ecological and genetic research and monitoring to inform conservation efforts; development of national and local policy initiatives;
• outreach to livestock owners to minimise conflict;
• and the development and provision of multimedia materials for a variety of audiences.

Further conservation measures should include efforts to assess and manage wild prey populations so that jaguars are not forced to hunt livestock, the enhancement of livestock management due to the impact of retaliatory killing of jaguars, the improvement of law enforcement to protect jaguars and their prey, and the creation of protected areas and strategic plans.