Jaguar
The jaguar (Panthera onca) is a large cat species and the only living member of the genus Panthera native to the Americas. With a body length of up to 1.85 m (6 ft 1 in) and a weight of up to 158 kg (348 lb), it is the largest cat species in the Americas and the third largest in the world. Its distinctively marked coat features pale yellow to tan colored fur covered by spots that transition to rosettes on the sides, although a melanistic black coat appears in some individuals. The jaguar's powerful bite allows it to pierce the carapaces of turtles and tortoises, and to employ an unusual killing method: it bites directly through the skull of mammalian prey between the ears to deliver a fatal blow to the brain.
Jaguar
The modern jaguar's ancestors probably entered the Americas from Eurasia during the Early Pleistocene via the land bridge that once spanned the Bering Strait. Today, the jaguar's range extends from core Southwestern United States across Mexico and much of Central America, the Amazon rainforest and south to Paraguay and northern Argentina. It inhabits a variety of forested and open terrains, but its preferred habitat is tropical and subtropical moist broadleaf forest, wetlands and wooded regions. It is adept at swimming and is largely a solitary, opportunistic, stalk-and-ambush apex predator. As a keystone species, it plays an important role in stabilizing ecosystems and in regulating prey populations.
In 1758, Carl Linnaeus described the jaguar in his work Systema Naturae and gave it the scientific name Felis onca.[11]In the 19th and 20th centuries, several jaguar type specimens formed the basis for descriptions of subspecies.[2] In 1939, Reginald Innes Pocock recognized eight subspecies based on the geographic origins and skull morphology of these specimens.[12]Pocock did not have access to sufficient zoological specimens to critically evaluate their subspecific status but expressed doubt about the status of several. Later consideration of his work suggested only three subspecies should be recognized. The description of P. o. palustris was based on a fossil skull.[4]
The Panthera lineage is estimated to have genetically diverged from the common ancestor of the Felidae around 9.32 to 4.47 million years ago to 11.75 to 0.97 million years ago,[24][25][26]and the geographic origin of the genus is most likely northern Central Asia.[27]Some genetic analyses place the jaguar as a sister species to the lion with which it diverged 3.46 to 1.22 million years ago,[24][25] but other studies place the lion closer to the leopard.[28][29]
The jaguar's coat ranges from pale yellow to tan or reddish-yellow, with a whitish underside and covered in black spots. The spots and their shapes vary: on the sides, they become rosettes which may include one or several dots. The spots on the head and neck are generally solid, as are those on the tail where they may merge to form bands near the end and create a black tip. They are elongated on the middle of the back, often connecting to create a median stripe, and blotchy on the belly.[4] These patterns serve as camouflage in areas with dense vegetation and patchy shadows.[40]Jaguars living in forests are often darker and considerably smaller than those living in open areas, possibly due to the smaller numbers of large, herbivorous prey in forest areas.[41]
The jaguar closely resembles the leopard but is generally more robust, with stockier limbs and a more square head. The rosettes on a jaguar's coat are larger, darker, fewer in number and have thicker lines, with a small spot in the middle.[38]It has powerful jaws with the third-highest bite force of all felids, after the tiger and the lion.[42]It has an average bite force at the canine tip of 887.0 Newton and a bite force quotient at the canine tip of 118.6.[43]A 100 kg (220 lb) jaguar can bite with a force of 4.939 kN (1,110 lbf) with the canine teeth and 6.922 kN (1,556 lbf) at the carnassial notch.[44]
Melanistic jaguars are also known as black panthers. The black morph is less common than the spotted one.[45]Black jaguars have been documented in Central and South America. Melanism in the jaguar is caused by deletions in the melanocortin 1 receptor gene and inherited through a dominant allele.[46]
In 2004, a camera trap in the Sierra Madre Occidental mountains photographed the first documented black jaguar in Northern Mexico.[47] Black jaguars were also photographed in Costa Rica's Alberto Manuel Brenes Biological Reserve, in the mountains of the Cordillera de Talamanca, in Barbilla National Park and in eastern Panama.[48][49][50][51]
In the 19th century, the jaguar was still sighted at the North Platte River in Colorado and coastal Louisiana.[52]In 1919, sightings of jaguars were reported in the Monterey, California region.[53]In 1999, its historic range at the turn of the 20th century was estimated at 19,000,000 km2 (7,300,000 sq mi), stretching from the southern United States through Central America to southern Argentina. By the turn of the 21st century, its global range had decreased to about 8,750,000 km2 (3,380,000 sq mi), with most declines in the southern United States, northern Mexico, northern Brazil, and southern Argentina.[54]Its present range extends from Mexico through Central America to South America comprising Belize, Guatemala, Honduras, Nicaragua, Costa Rica, particularly on the Osa Peninsula, Panama, Colombia, Venezuela, Guyana, Suriname, French Guiana, Ecuador, Peru, Bolivia, Brazil, Paraguay and Argentina. It is considered to be locally extinct in El Salvador and Uruguay.[1]
The jaguar prefers dense forest and typically inhabits dry deciduous forests, tropical and subtropical moist broadleaf forests, rainforests and cloud forests in Central and South America; open, seasonally flooded wetlands, dry grassland and historically also oak forests in the United States. It has been recorded at elevations up to 3,800 m (12,500 ft) but avoids montane forests. It favors riverine habitat and swamps with dense vegetation cover.[41] In the Mayan forests of Mexico and Guatemala, 11 GPS-collared jaguars preferred undisturbed dense habitat away from roads; females avoided even areas with low levels of human activity, whereas males appeared less disturbed by human population density.[58] A young male jaguar was also recorded in the semi-arid Sierra de San Carlos at a waterhole.[59]
The jaguar is mostly active at night and during twilight.[60][61][62]However, jaguars living in densely forested regions of the Amazon Rainforest and the Pantanal are largely active by day, whereas jaguars in the Atlantic Forest are primarily active by night.[63]The activity pattern of the jaguar coincides with the activity of its main prey species.[64] Jaguars are good swimmers and play and hunt in the water, possibly more than tigers. They have been recorded moving between islands and the shore. Jaguars are also good at climbing trees but do so less often than cougars.[4]
The adult jaguar is an apex predator, meaning it is at the top of the food chain and is not preyed upon in the wild. The jaguar has also been termed a keystone species, as it is assumed that it controls the population levels of prey such as herbivorous and seed-eating mammals and thus maintains the structural integrity of forest systems.[39][65][66]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.[67]
The jaguar is sympatric with the cougar (Puma concolor). In central Mexico, both prey on white-tailed deer (Odocoileus virginianus), which makes up 54% and 66% of jaguar and cougar's prey, respectively.[39] In northern Mexico, the jaguar and the cougar share the same habitat, and their diet overlaps dependent on prey availability. Jaguars seemed to prefer deer and calves. In Mexico and Central America, neither of the two cats are considered to be the dominant predator.[68]In South America, the jaguar is larger than the cougar and tends to take larger prey, usually over 22 kg (49 lb). The cougar's prey usually weighs between 2 and 22 kg (4 and 49 lb), which is thought to be the reason for its smaller size.[69]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.[39]
The jaguar's bite force allows it to pierce the carapaces of the yellow-spotted Amazon river turtle (Podocnemis unifilis) and the yellow-footed tortoise (Chelonoidis denticulatus).[74][75] It employs an unusual killing method: it bites mammalian prey directly through the skull between the ears to deliver a fatal bite to the brain.[76] It kills capybara by piercing its canine teeth through the temporal bones of its skull, breaking its zygomatic arch and mandible and penetrating its brain, often through the ears.[77]It has been hypothesized to be an adaptation to "cracking open" turtle shells; armored reptiles may have formed an abundant prey base for the jaguar following the late Pleistocene extinctions.[74] However, this is disputed, as even in areas where jaguars prey on reptiles, they are still taken relatively infrequently compared to mammals in spite of their greater abundance.[70]
Between October 2001 and April 2004, 10 jaguars were monitored in the southern Pantanal. In the dry season from April to September, they killed prey at intervals ranging from one to seven days; and ranging from one to 16 days in the wet season from October to March.[78]
The jaguar uses a stalk-and-ambush strategy when hunting rather than chasing prey. The cat will slowly walk 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. After killing prey, the jaguar will drag the carcass to a thicket or other secluded spot. It begins eating at the neck and chest. The heart and lungs are consumed, followed by the shoulders.[79] 041b061a72