Social structure

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[36]) 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.[36][38] Scrape marks, urine, and feces are used to mark territory.[39]

Like the other big cats, the jaguar is capable of roaring (the male more powerfully) and does so to warn territorial and mating competitors away; intensive bouts of counter-calling between individuals have been observed in the wild.[40] Their roar often resembles a repetitive cough, and they may also vocalize mews and grunts.[27] Mating fights between males occur, but are rare, and aggression avoidance behaviour has been observed in the wild.[39] When it occurs, conflict is typically over territory: a male's range may encompass that of two or three females, and he will not tolerate intrusions by other adult males.[36]

The jaguar is often described as nocturnal, but is more specifically crepuscular (peak activity around dawn and dusk). Both sexes hunt, but males travel farther each day than females, befitting their larger territories. The jaguar may hunt during the day if game is available and is a relatively energetic feline, spending as much as 50–60% of its time active.[28] The jaguar's elusive nature and the inaccessibility of much of its preferred habitat make it a difficult animal to sight, let alone study.

[edit] Hunting and diet

Like all cats, the jaguar is an obligate carnivore, feeding only on meat. It is an opportunistic hunter and its diet encompasses 85 species.[28] The jaguar prefers large prey and will take deer, tapirs, peccaries, dogs, and even anacondas and caiman. However, the cat will eat any small species that can be caught, including frogs, mice, birds, fish, sloths, monkeys, turtles, capybara, and domestic livestock.[41]

While the jaguar employs the deep-throat bite-and-suffocation technique typical among Panthera, it prefers a killing method unique amongst cats: it pierces directly through the temporal bones of the skull between the ears of prey (especially the Capybara) with its canine teeth, piercing the brain. This may be an adaptation to "cracking open" turtle shells; following the late Pleistocene extinctions, armoured reptiles such as turtles would have formed an abundant prey base for the jaguar.[40][28] The skull bite is employed with mammals in particular; with reptiles such as caiman, the jaguar may leap on to the back of the prey and sever the cervical vertebrae, immobilizing the target. While capable of cracking turtle shells, the jaguar may simply reach into the shell and scoop out the flesh.[36] With prey such as dogs, a paw swipe to crush the skull may be sufficient.

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.[36]

On killing prey, the jaguar will drag the carcass to a thicket or other secluded spot. It begins eating at the neck and chest, rather than the midsection. The heart and lungs are consumed, followed by the shoulders.[36] The daily food requirement of a 34 kilogram animal, at the extreme low end of the species' weight range, has been estimated at 1.4 kilograms.[42] For captive animals in the 50–60 kilogram range, more than 2 kilograms of meat daily is recommended.[43] In the wild, consumption is naturally more erratic; wild cats expend considerable energy in the capture and kill of prey, and may consume up to 25 kilograms of meat at one feeding, followed by periods of famine.[44]

[edit] Ecology

[edit] Distribution and habitat

The jaguar has been attested in the fossil record for two million years[23] 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.[22] Its present range extends from Mexico, through Central America and into South America, including much of Amazonian Brazil.[45] 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, U.S. and Venezuela. The jaguar is now extinct in El Salvador and Uruguay.[2] The largest protected jaguar habitat is the 400 square kilometer Cockscomb Basin Wildlife Sanctuary in Belize.

The inclusion of the United States in the list is based on occasional sightings in the southwest, particularly in Arizona, New Mexico and Texas. In the early 1900s, the jaguar's range extended as far north as Southern California and western Texas.[42] The jaguar is a protected species in the United States under the Endangered Species Act, which has stopped the shooting of the animal for its pelt. In 2004, wildlife officials in Arizona photographed and documented jaguars in the southern part of the state. For any permanent population to thrive, protection from killing, an adequate prey base, and connectivity with Mexican populations are essential.[46]

The historic range of the species included much of the southern half of the United States, and in the south extended much farther to cover most of the South American continent. In total, its northern range has receded 1000 kilometers southward and its southern range 2000 km northward. Ice Age fossils of the jaguar, dated between 40,000 and 11,500 years ago, have been discovered in the United States, including some at an important site as far north as Missouri. Fossil evidence shows jaguars of up to 190 kg (420 lb), much larger than the contemporary average for the animal.[47]

The habitat of the cat includes the rain forests of South and Central America, open, seasonally flooded wetlands, and dry grassland terrain. Of these habitats, the jaguar much prefers dense forest;[28] the cat has lost range most rapidly in regions of drier habitat, such as the Argentinian pampas, the arid grasslands of Mexico, and the southwestern United States.[2] The cat will range across tropical, subtropical, and dry deciduous forests (including, historically, oak forests in the United States). The jaguar is strongly associated with water and it often prefers to live by rivers, swamps, and in dense rainforest with thick cover for stalking prey. Jaguars have been found at elevations as high as 3800 m, but they typically avoid mountain forest and are not found in the high plateau of central Mexico or in the Andes.[28]

[edit] Ecological role
A jaguar in a wildlife rescue & rehabilitation centre in Argentina.
A jaguar in a wildlife rescue & rehabilitation centre in Argentina.

The jaguar is an apex predator, meaning that it exists at the top of its food chain and is not regularly preyed on in the wild. The jaguar has also been termed a keystone species, as it is assumed, through controlling the population levels of prey such as herbivorous and granivorous mammals, apex felids maintain the structural integrity of forest systems.[26][48] However, accurately determining what effect species like the jaguar have on ecosystems is difficult, because data must be compared from regions where the species is absent as well as its current habitats, while controlling for the effects of human activity. It is accepted that mid-sized prey species see population increases in the absence of the keystone predators and it has been hypothesized that this has cascading negative effects,[49] however, field work has shown this may be natural variability and that the population increases may not be sustained. Thus, the keystone predator hypothesis is not favoured by all scientists.[50]

The jaguar also has an effect on other predators. The jaguar and the cougar, the next largest feline of the Americas, are often sympatric (related species sharing overlapping territory) and have often been studied in conjunction. Where sympatric with the jaguar, the cougar is smaller than normal. The jaguar tends to take larger prey and the cougar smaller, reducing the latter's size.[51] This situation may be advantageous to the cougar. Its broader prey niche, including its ability to take smaller prey, may give it an advantage over the jaguar in human-altered landscapes;[26] while both are classified as near-threatened species, the cougar has a significantly larger current distribution.

[edit] Conservation status
Jaguar at Toronto Zoo
Jaguar at Toronto Zoo

Jaguar populations are currently declining. The animal is considered near-threatened by the International Union for Conservation of Nature and Natural Resources,[2] meaning it may be threatened with extinction in the near future. The loss of parts of its range, including its virtual elimination from its historic northern areas and the increasing fragmentation of the remaining range, have contributed to this status. The 1960s saw particularly significant declines, with more than 15,000 jaguar skins brought out of the Brazilian Amazon yearly; the Convention on International Trade in Endangered Species (CITES) of 1973 brought about a sharp decline in the pelt trade.[52] Detailed work performed under the auspices of the Wildlife Conservation Society reveal that the animal has lost 37% of its historic range, with its status unknown in an additional 18%. More encouragingly, the probability of long-term survival was considered high in 70% of its remaining range, particularly in the Amazon basin and the adjoining Gran Chaco and Pantanal.[45]

The major risks to the jaguar include deforestation across its habitat, increasing competition for food with human beings,[2] poaching, hurricanes in Northern parts of its range, and the behaviour of ranchers who will often kill the cat where it preys on livestock. When adapted to the prey, the jaguars has been shown to take cattle as a large portion of its diet; while land clearance for grazing is a problem for the species, the jaguar population may have increased when cattle were first introduced to South America as the animals took advantage of the new prey base. This willingness to take livestock has induced ranch owners to hire full-time jaguar hunters, and the cat is often shot on sight.[27]
The Pantanal, Brazil in flood condition, a critical jaguar range area.
The Pantanal, Brazil in flood condition, a critical jaguar range area.

The jaguar is regulated as an Appendix I species under CITES: all international trade in jaguars or their parts is prohibited. All hunting of jaguars is prohibited in Argentina, Belize, Colombia, French Guiana, Honduras, Nicaragua, Panama, Paraguay, Suriname, the United States (where it is listed as endangered under the Endangered Species Act), Uruguay and Venezuela. Hunting of jaguars is restricted to "problem animals" in Brazil, Costa Rica, Guatemala, Mexico and Peru, while trophy hunting is still permitted in Bolivia. The species has no legal protection in Ecuador or Guyana.[23]

Current conservation efforts often focus on educating ranch owners and promoting ecotourism.[53] The jaguar is generally defined as an "umbrella species"—a species whose home range and habitat requirements are sufficiently broad that, if protected, numerous other species of smaller range will also be protected.[54] Umbrella species serve as "mobile links" at the landscape scale, in the jaguar's case through predation. Conservation organizations may thus focus on providing viable, connected habitat for the jaguar, with the knowledge that other species will also benefit.[53]

Given the inaccessibility of much of the species' range—particularly the central Amazon—estimating jaguar numbers is difficult. Researchers typically focus on particular bioregions, and thus species-wide analysis is scant. In 1991, 600–1,000 (the highest total) were estimated to be living in Belize. A year earlier, 125–180 jaguars were estimated to be living in Mexico's 4,000 square kilometer (2400 mi²) Calakmul Biosphere Reserve, with another 350 in the state of Chiapas. The adjoining Maya Biosphere Reserve in Guatemala, with an area measuring 15,000 square kilometers (9,000 mi²), may have 465–550 animals.[55] Work employing GPS-telemetry in 2003 and 2004 found densities of only six to seven jaguars per 100 square kilometers in the critical Pantanal region, compared with 10 to 11 using traditional methods; this suggests that widely used sampling methods may inflate the actual numbers of cats.[56]

On 7 January, 2008 United States Fish and Wildlife Service Director H. Dale Hall approved an unprecedented decision by the George W. Bush Administration to abandon jaguar recovery as a federal goal under the Endangered Species Act. The decision is the first of its kind in the 34-year history of the Endangered Species Act. Some critics of the decision said that the jaguar is being sacrificed for the government's new border fence, which is to be built along many of the cat's typical crossings between the United States and Mexico