A black panther is a black (melanistic) color variant of one of several species of larger cat which are often known by the term panther. "Panther" in North America is most commonly used for the cougar (genus Puma), in Latin America it is most often used to mean a jaguar and elsewhere in the world it usually refers to the leopard (both genus Panthera). Panthers are not necessarily black, but may also be normally colored for the species (tawny or spotted), or white. They are the namesake for the Black Panther Party.
It is thought that melanism may confer a selective advantage under certain conditions since it is more common in regions of dense forest, where light levels are lower. Recent, preliminary studies also suggest that melanism might be linked to beneficial mutations in the immune system.
Black leopards are reported from most densely forested areas in southwestern China, Myanmar, Assam and Nepal, from Travancore and other parts of southern India and are said to be common in Java and the southern part of the Malay Peninsula where they may be more numerous than spotted leopards. They are less common in tropical Africa, but have been reported from Ethiopia (formerly Abyssinia), from the forests of Mount Kenya and from the Aberdares. One was recorded by Peter Turnbull-Kemp in the equatorial forest of Cameroon.
It is a myth that black leopards are often rejected by their mothers at an early age because of their color. In actuality, poor temperament has been bred into the captive strains as a side-effect of inbreeding and it is this poor temperament that leads to problems of maternal care in captivity. According to Funk and Wagnalls' Wildlife Encyclopedia, captive black leopards are less fertile than normal leopards, with average litter sizes of 1.8 and 2.1, respectively. This is likely due to inbreeding depression.
In the early 1980s, the Glasgow Zoo, in Scotland, acquired a 10 year old black leopard, nicknamed the Cobweb Panther, from the Dublin Zoo in Ireland. She was exhibited for several years before being moved to the Madrid Zoo, in Spain. This leopard had a uniformly black coat profusely sprinkled with white hairs as though draped with spider webs. The condition appeared to be vitiligo; as she aged, the white became more extensive. Since then, other "Cobweb Panthers" have been reported and photographed in zoos.
In Harmsworth Natural History (1910), WH Hudson writes:
The jaguar is a beautiful creature, the ground-colour of the fur a rich golden-red tan, abundantly marked with black rings, enclosing one or two small spots within. This is the typical colouring, and it varies little in the temperate regions; in the hot region the Indians recognise three strongly marked varieties, which they regard as distinct species – the one described; the smaller jaguar, less aquatic in his habits and marked with spots, not rings; and, thirdly, the black variety. They scout the notion that their terrible "black tiger" is a mere melanic variation, like the black leopard of the Old World and the wild black rabbit. They regard it as wholly distinct, and affirm that it is larger and much more dangerous than the spotted jaguar; that they recognise it by its cry; that it belongs to the terra firma rather than to the water-side; finally, that black pairs with black, and that the cubs are invariably black. Nevertheless, naturalists have been obliged to make it specifically one with Felis onca, the familiar spotted jaguar, since, when stripped of its hide, it is found to be anatomically as much like that beast as the black is like the spotted leopard.
The gene is incompletely dominant. Individuals with two copies of the gene are darker (the black background colour is more dense) than individuals with just one copy whose background colour may appear to be dark charcoal rather than black.
A black jaguar, named "Diablo", was inadvertently crossed with a lioness, named "Lola", at the Bear Creek Wildlife Sanctuary in Barrie, Canada. The offspring were a charcoal black jaglion female and a tan-colored, spotted jaglion male. It therefore appears that the jaguar melanism gene is also dominant over normal lion coloration (the black jaguar sire was presumably carrying the black on only one allele).
In his Histoire Naturelle (1749), Georges-Louis Leclerc, Comte de Buffon, wrote of the "Black Cougar":
"M. de la Borde, King’s physician at Cayenne, informs me, that in the [South American] Continent there are three species of rapacious animals; that the first is the jaguar, which is called the tiger; that the second is the couguar [sic], called the red tiger, on account of the uniform redness of his hair; that the jaguar is of the size of a large bull-dog, and weighs about 200 pounds (90 kg); that the couguar is smaller, less dangerous, and not so frequent in the neighbourhood of Cayenne as the jaguar; and that both these animals take six years in acquiring their full growth. He adds, that there is a third species in these countries, called the black tiger, of which we have given a figure under the appellation of the black couguar. The head is pretty similar to that of the common cougar; but the animal has long black hair, and likewise a long tail, with strong whiskers. He weighs not much above forty pounds. The female brings forth her young in the hollows of old trees."This "black couguar" was most likely a margay or ocelot, which are under forty pounds in weight, live in trees, and occur in a melanistic phase.
Another description of a black cougar was provided by Pennant: According to his translator Smellie (1781), the description was taken from two black cougars exhibited in London some years previously.
The Academy specimen, upon close examination, is far from black. The most heavily pigmented portions are the crown and dorsal area. In most lights these areas appear black, but at certain angles the dorsal strip has a decidedly mahogany tint. The mahogany coloring becomes lighter and richer on the sides. The underparts are lightest, being almost ferruginous in color. The chin, throat and cheeks are dark chocolate-brown, but the facial stripes can be seen clearly. The limbs are dark mahogany. In certain lights the typical spot-pattern of the Florida bobcat can be distinctly seen on the side, underparts and limbs. The Bronx Park animal appears darker and the spots are not visible, although the poor light in the quarantine cage may have been the reason.Adult male bobcats are 28–47 in (70–120 cm) long, with a short, bobbed tail, and are 18–24 in (45–60 cm) high at the shoulder. Females are slightly smaller. Florida cougars are 23–32 in (60–80 cm) at the shoulder and 5–7 ft (1.5–2.1 m) long, including the tail. Bobcats weigh 16–30 lb (7–14 kg) while Florida cougars are 50–150 lb (23–70 kg).
Another possible explanation for black cougar sightings is the jaguarundi, a cat very similar genetically to the cougar, which grows to around 30 in (75 cm) with an additional 20 in (50 cm) of tail. Their coat goes through a reddish-brown phase and a dark grey phase. While their acknowledged natural range ends in southern Texas, a small breeding population was introduced to Florida in the 1940s, and there are rumors of people breeding them as pets there as well. In Central America, they are known as relatively docile pets, as far as non-domesticated animals go. The male jaguarundi's home range can be up to 100 km² (39 sq mi) while the female's home range can be as large as 20 km² (8 sq mi). It has been suggested that very small populations of jaguarundi, which rarely venture out of deep forests, are responsible for many or most of the supposed black cougar sightings. While they are significantly smaller than a cougar, differently colored, and much lower to the ground (many note a resemblance to the weasel), memory bias could explain many of the sightings in the southeastern U.S.
Another possibility would be the black jaguar which ranged into North America in historical memory. Melanistic jaguars are uncommon in nature and, significantly, jaguars in general were persecuted to near-extinction in the 1960s. Though they do not look exactly like cougars, they have the requisite size; it is conceivable that there could be a breeding population hidden in, for example, the Louisiana bayou. The jaguar has had several (photographically) confirmed, and many unconfirmed, sightings in Arizona, New Mexico, Oklahoma, and southwest Texas, but not beyond that region.