COMMON NAME: Jaguar
SCIENTIFIC NAME: Panthera onca
AVERAGE LIFE SPAN IN THE WILD: 12 to 15 years
SIZE: Head and body, 5 to 6 ft; tail, 27.5 to 36 in
WEIGHT: 100 to 250 lbs
SIZE RELATIVE TO A 6-FT MAN:
A melanistic jaguar is a color morph which occurs at about 6 percent frequency in populations. Melanistic jaguars are informally known as black panthers, but as with all forms of polymorphism they do not form a separate species. The black morph is less common than the spotted morph, estimated at occurring in about 6% of the South American jaguar population. In Mexico’s Sierra Madre Occidental, the first black jaguar was recorded in 2004.
Some evidence indicates that the melanistic allele is dominant, and being supported by natural selection. The black form may be an example of heterozygote advantage; breeding in captivity is not yet conclusive on this. Melanistic jaguars (or “black” jaguars) occur primarily in parts of South America, and are virtually unknown in wild populations residing in the subtropical and temperate regions of North America; they have never been documented north of Mexico’s Isthmus of Tehuantepec.
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.
Jaguars at Cameron Park Zoo in Waco, Texas
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 territory of a male can contain those of several females. 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
The jaguar has an exceptionally powerful bite that allows it to pierce the shells of armored prey. 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. It employs 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 can take virtually any terrestrial or riparian vertebrate found in Central or South America, except for large crocodilians such as black caiman. Jaguars are excellent swimmers and will dive under the water to catch turtles in rivers and the occasional fish. 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, except for black caimans, deer, capybaras, tapirs, peccaries, dogs, zorros, and sometimes even anacondas. However, it preys on any small species available, 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 revealed that the diet of jaguars there consisted primarily of armadillos and pacas. Some jaguars will also take domestic livestock. El Jefe, one of the few jaguars that were reported in the United States, has also been found to kill and eat American black bears, as deduced from hairs found within his scats and the partly consumed carcass of a black bear sow with the distinctive puncture marks to the skull left by jaguars. This indicates that jaguars might have once preyed on black bears when the species was still present in the area. Spectacled bears are also known to avoid jaguars, possibly because they may constitute occasional prey items.
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 turtle 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.
Illustration of a jaguar killing a tapir, the largest native land animal in its range
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.
Rtr. Sethil Muhandiram