Jaguar

The jaguar (Panthera onca) is a big cat, a feline in the Panthera genus, and is the only extant Panthera species native to the Americas. The jaguar is the third-largest feline after the tiger and the lion, and the largest in the Americas. The jaguar's present range extends from Southwestern United States and Mexico across much of Central America and south to Paraguay and northern Argentina. Apart from a known and possibly breeding population in Arizona(southeast of Tucson) and the bootheel of New Mexico, the cat has largely been extirpated from the United States since the early 20th century.

This spotted cat most closely resembles the leopard physically, although it is usually larger and of sturdier build and its behavioral and habitat characteristics are closer to those of the tiger. While dense rainforest is its preferred habitat, the jaguar will range across a variety of forested and open terrains. Its preferred habitats are usually swamps and wooded regions, but jaguars also live in scrublands and deserts. The jaguar is notable, along with the tiger, as a feline that enjoys swimming. The jaguar is largely a solitary, opportunistic, stalk-and-ambush predator at the top of the food chain (an apex predator). It is a keystone species, playing an important role in stabilizing ecosystems and regulating the populations of the animals it hunts. The jaguar has an exceptionally powerful bite, even relative to the other big cats. This allows it to pierce the shells of armored reptiles and to employ an unusual killing method: it bites directly through the skull of prey between the ears to deliver a fatal bite to the brain.

The jaguar is a near threatened species and its numbers are declining. Threats include loss and fragmentation of habitat. While international trade in jaguars or their parts is prohibited, the cat is still frequently killed by humans, particularly in conflicts with ranchers and farmers in South America. Although reduced, its range remains large. Given its historical distribution, the jaguar has featured prominently in the mythology of numerous indigenous American cultures, including those of the Maya and Aztec.

Biology and Behavior[]

Physical Characteristics[]

The jaguar, a compact and well-muscled animal, is the largest cat in the New World and the largest carnivorous mammal in Central and South America. Size and weight vary considerably: weights are normally in the range of 56–96 kg (124–211 lb). Larger males have been recorded to weigh as much as 158 kg (348 lb) (roughly matching a tigress or lioness; however note this animal was weighed with a full stomach). The smallest females have low weights of 36 kg (79 lb). Females are typically 10–20 percent smaller than males. The length, from the nose to the base of the tail, of the cats varies from 1.12 to 1.85 m (3.7 to 6.1 ft). Their tails are the shortest of any big cat, at 45 to 75 cm (18 to 30 in) in length. Their legs are also short, considerably shorter when compared to a small tiger or lion in a similar weight range, but are thick and powerful. The jaguar stands 63 to 76 cm (25 to 30 in) tall at the shoulders. Compared to the similarly colored Old World leopard, the jaguar is bigger, heavier and relatively stocky in build.

Further variations in size have been observed across regions and habitats, with size tending to increase from the north to south. A study of the jaguar in the Chamela-Cuixmala Biosphere Reserve on the Mexican Pacific coast, showed ranges of just about 50 kg (110 lb), about the size of a female cougar. Jaguars in Venezuela or Brazil are much larger with average weights of about 95 kg (220 lb) in males and of about 56 kilograms (123 lb) to 78 kilograms (172 lb) in females. In the Brazilian Pantanal, weights of 136 kilograms (300 lb) or more are not uncommon in old males, with the highest recorded weight, for a Jaguar weighed on an empty stomach being 148 kilograms (326 lb). Forest jaguars are frequently darker and considerably smaller than those found in open areas (the Pantanal is an open wetland basin), possibly due to the smaller numbers of large, herbivorous prey in forest areas.

A short and stocky limb structure makes the jaguar adept at climbing, crawling, and swimming. The head is robust and the jaw extremely powerful, it has the third highest bite force of all felids, after the lion and tiger. A 100 kg (220 lb) jaguar can bite with a force of 503.57 kgf (1110 lbf) at canine teeth and 705.79 kgf (1556 lbf) at carnassial notch. This strength adaptation allows the jaguar to pierce turtle shells. A comparative study of bite force adjusted for body size ranked it as the top felid, alongside the clouded leopard and ahead of the lion and tiger. It has been reported that "an individual jaguar can drag an 800 lb (360 kg) bull 25 ft (7.6 m) in its jaws and pulverize the heaviest bones". The jaguar hunts wild animals weighing up to 300 kg (660 lb) in dense jungle, and its short and sturdy physique is thus an adaptation to its prey and environment.

Coloration[]

The base coat of the jaguar is generally a tawny yellow, but can range to reddish-brown and black, for most of the body. However, the ventral areas are white. The cat is covered in rosettes for camouflage in the dappled light of its forest habitat. The spots vary over individual coats and between individual jaguars: rosettes may include one or several dots, and the shapes of the dots vary. The spots on the head and neck are generally solid, as are those on the tail, where they may merge to form a band.

While the jaguar closely resembles the leopard, it 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.

Color Morphism[]

Color morphism occurs in the species. A near-black melanistic form occurs regularly. Jaguars with melanism appear entirely black, although their spots are still visible on close examination. The black morph is less common than the spotted form but, at about six percent of the population, it is several orders of magnitude above the mutation rate. Hence, it is being supported by selection. Some evidence indicates the melanism allele is dominant. The black form may be an example of heterozygote advantage; breeding in captivity is not yet conclusive on this.

Melanistic jaguars are informally known as black panthers, but (as with all forms of polymorphism) they do not form a separate species. Extremely rare albino individuals, sometimes called white panthers, also occur among jaguars, as with the other big cats. As usual with albinos in the wild, selection keeps the frequency close to the rate of mutation.

Reproduction and Life Cycle[]

Jaguar females reach sexual maturity at about two years of age, and males at three or four. The cat is believed to mate throughout the year in the wild, although births may increase when prey is plentiful. Research on captive male jaguars supports the year-round mating hypothesis, with no seasonal variation in semen traits and ejaculatory quality; low reproductive success has also been observed in captivity. Female estrus is 6–17 days out of a full 37-day cycle, and females will advertise fertility with urinary scent marks and increased vocalization. Both sexes will range more widely than usual during courtship.

Pairs separate after mating, and females provide all parenting. The gestation period lasts 93–105 days; females give birth to up to four cubs, and most commonly to two. The mother will not tolerate the presence of males after the birth of cubs, given a risk of infanticide; this behavior is also found in the tiger.

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. They will continue in their mother's company for one to two years before leaving to establish a territory for themselves. Young males are at first nomadic, jostling with their older counterparts until they succeed in claiming a territory. 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.

Social Activity[]

Like most cats, the jaguar is solitary outside mother–cub groups. Adults generally meet only to court and mate (though limited noncourting socialization has been observed anecdotally) and carve out large territories for themselves. Female territories, which range from 25 to 40 km² 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. The jaguar uses scrape marks, urine, and feces to mark its territory.

Like the other big cats, the jaguar is capable of roaring and does so to warn territorial and mating competitors away; intensive bouts of counter-calling between individuals have been observed in the wild. Their roar often resembles a repetitive cough, and they may also vocalize mews and grunts. Mating fights between males occur, but are rare, and aggression avoidance behavior has been observed in the wild. 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.

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 percent of its time active. The jaguar's elusive nature and the inaccessibility of much of its preferred habitat make it a difficult animal to sight, let alone study.

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 at least 87 species. The jaguar can take virtually any terrestrial or riparian vertebrate found in Central or South America, with a preference for large prey. The jaguar is more of a dietary generalist than its Old World cousins: the American tropics have a high diversity of small animals but relatively low populations and diversity of the large ungulates which this genus favors. They regularly take adult caimans, deer, capybaras, tapirs, peccaries, dogs, zorros, and sometimes even anacondas. However, the cat will eat any small species that can be caught, including frogs, mice, birds (mainly ground-based species such as cracids), fish, sloths, monkeys, and turtles; a study conducted in Cockscomb Basin Wildlife Sanctuary in Belize, for example, revealed that the diets of jaguars there consisted primarily of armadillos and pacas. Some jaguars will also take domestic livestock. There is evidence that jaguars in the wild consume the roots of Banisteriopsis caapi.

While the jaguar often employs the deep throat-bite and suffocation technique typical among Panthera, it sometimes uses 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, armored reptiles such as turtles would have formed an abundant prey base for the jaguar. The skull bite is employed with mammals in particular; with reptiles such as the caiman, the jaguar may leap onto the back of the prey and sever the cervical vertebrae, immobilizing the target. When attacking sea turtles, including the huge Leatherback sea turtles which weighs about 385 kg (849 lb) on average, as they try to nest on beaches, the jaguar will bite at the head, often beheading the prey, before dragging it off to eat. Reportedly, while hunting horses, a jaguar may leap onto their back, place one paw on the muzzle and another on the nape and then twist, dislocating the neck. Local people have anecdotally reported that when hunting a pair of horses bound together, the jaguar will kill one horse and then drag it while the other horse, still living, is dragged in their wake. With prey such as smaller dogs, a paw swipe to the skull may be sufficient to kill it.

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.

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. The daily food requirement of a 34 kg (75 lb) animal, at the extreme low end of the species' weight range, has been estimated at 1.4 kg (3.1 lb). For captive animals in the 50–60 kg (110–130 lb) range, more than 2 kg (4.4 lb) of meat daily are recommended. In the wild, consumption is naturally more erratic; wild cats expend considerable energy in the capture and kill of prey, and they may consume up to 25 kg (55 lb) of meat at one feeding, followed by periods of famine. Unlike all other Panthera species, jaguars very rarely attack humans. However, jaguar attacks appear to be on the rise with increased human encroachment on their habitat and a decrease in prey populations. Sometimes jaguars in captivity attack zookeepers.

Ecology[]

Distribution and Habitat[]

The jaguar has been an American cat since crossing the Bering Land Bridge during the Pleistocene epoch; 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 (particularly on the Osa Peninsula), Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, the United States and Venezuela. The jaguar is now extinct in El Salvador and Uruguay. It occurs in the 400 km² Cockscomb Basin Wildlife Sanctuary in Belize, the 5,300 km² Sian Ka'an Biosphere Reserve in Mexico, the approximately 15,000 km² Manú National Park in Peru, the approximately 26,000 km² Xingu National Park in Brazil, and numerous other reserves throughout its range.

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 20th century, the jaguar's range extended as far north as the Grand Canyon, and as far west as Southern California. 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 1996 and from 2004 on, wildlife officials in Arizona photographed and documented jaguars in the southern part of the state. Between 2004 and 2007, two or three jaguars have been reported by researchers around Buenos Aires National Wildlife Refuge in southern Arizona. One of them, called 'Macho B', had been previously photographed in 1996 in the area. For any permanent population in the USA to thrive, protection from killing, an adequate prey base, and connectivity with Mexican populations are essential. In February 2009, a 53.5 kg (118 lb) jaguar was caught, radio-collared and released in an area southwest of Tucson, Arizona; this is farther north than had previously been expected and represents a sign there may be a permanent breeding population of jaguars within southern Arizona. The animal was later confirmed to be indeed the same male individual ('Macho B') that was photographed in 2004. On 2 March 2009, Macho B was recaptured and euthanized after he was found to be suffering from kidney failure; the animal was thought to be 16 years old, older than any known wild jaguar.

Completion of the United States–Mexico barrier as currently proposed will reduce the viability of any population currently residing in the United States, by reducing gene flow with Mexican populations, and prevent any further northward expansion for the species. 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 1,000 km (621 mi) southward and its southern range 2,000 km (1243 mi) 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.

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; the cat has lost range most rapidly in regions of drier habitat, such as the Argentine pampas, the arid grasslands of Mexico, and the southwestern United States. The cat will range across tropical, subtropical, and dry deciduous forests (including, historically, oak forests in the United States). The jaguar 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 3,800 m, but they typically avoid montane forest and are not found in the high plateau of central Mexico or in the Andes. The jaguars preferred habitats are usually swamps and wooded regions, but jaguars also live in scrublands and deserts.

Ecological Role[]

The adult jaguar is an apex predator, meaning it exists at the top of its food chain and is not 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. 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 undergo population increases in the absence of the keystone predators, and this has been hypothesized to have cascading negative effects. However, field work has shown this may be natural variability and the population increases may not be sustained. Thus, the keystone predator hypothesis is not accepted by all scientists.

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 and is smaller than the local jaguars. The jaguar tends to take larger prey, usually over 22 kg (49 lb) and the cougar smaller, usually between 2 and 22 kg (4.4 and 48.5 lb), reducing the latter's size. 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; while both are classified as near-threatened species, the cougar has a significantly larger current distribution.