While “black tigers” do not exist as a separate species, tigers exhibiting a rare genetic condition called melanism have been observed. This condition causes their stripes to widen and merge, resulting in a very dark, often striking appearance. These unique tigers are extremely rare variants of existing tiger populations.
The Science of Melanism
Melanism is a biological phenomenon characterized by an increased production of melanin, the dark pigment responsible for coloration in skin, hair, and eyes. In tigers, this condition is often referred to as “pseudo-melanism” because their coats are not entirely black, but rather feature significantly broadened and closely spaced black stripes that obscure the underlying orange or tawny fur.
This distinctive coat pattern results from a single genetic mutation in the Transmembrane Aminopeptidase Q (Taqpep) gene. The Taqpep gene influences stripe patterns in various cat species; similar mutations are responsible for the blotchy patterns seen in king cheetahs and certain tabby cats. For a tiger cub to exhibit this darker coloration, it typically needs to inherit the mutated gene from both parents, highlighting the rarity of its manifestation.
Documented Cases and Rarity
Sightings of unusually dark tigers have been reported for centuries, with early documentation including a watercolor painting from 1773. However, definitive proof emerged later, notably with a confiscated pelt in 1993 and the birth of oddly patterned cubs in the Oklahoma City Zoo in the late 1990s.
Today, the most significant population of melanistic tigers is found exclusively in the Similipal Tiger Reserve in Odisha, India. Recent estimations from 2023-2024 indicate that at least 13 adult melanistic tigers, comprising seven females and six males, reside within Similipal’s population of 27 tigers. The high prevalence of this mutation in Similipal is attributed to the tiger population’s isolation, which has led to inbreeding within a small founding group. This genetic isolation and subsequent inbreeding increase the likelihood of recessive genes, like the one causing melanism, becoming more common.
Distinguishing Them from Subspecies
Melanistic tigers are not a separate species or subspecies, but rather a rare color variant of the Bengal tiger (Panthera tigris tigris). They are considered phenotypic mutations, meaning they are variations within an existing lineage rather than a distinct evolutionary branch. Their classification as “pseudo-melanistic” emphasizes that their coats are not uniformly black like true melanism, but rather display an extreme form of striping. This distinction is important to avoid misconceptions about their taxonomic status. The unique traits of these tigers are a result of genetic anomalies within an isolated population, not an indication of a new type of tiger.