The reason behind the majestic black stripes of melanistic tigers is mutation.
A black tiger was seen marking its territory, in a rare sighting from Odisha's Similipal National Park. It was seen leaving scratch marks on a tree in the 15-second clip posted on Twitter on the occasion of International Tigers Day.
"Sharing an interesting clip of a rare melanistic tiger marking its territory on international Tigers day," wrote Indian Forest Service Officer Susanta Nanda while sharing the clip.
The black or pseudo-melanistic tigers - with distinctive dark stripe pattern on a light background of white or golden - are rare and have only been camera-trapped in Similipal till date.
The officer, who is known to share interesting wildlife videos on Twitter, said the black tigers have a unique gene pool and the tiger reserve is poised for a recovery in their numbers.
The reason behind the majestic black stripes of melanistic tigers is mutation. They are Bengal tigers with a single base mutation in a particular gene. This mutation causes the tigers' distinctive black stripes to enlarge and spread into the orange background.
Different mutations in this particular gene cause identical changes in the coat colour of other species of cats including cheetahs.
Scientists speculate that Simlipal tiger may have come from a small founding population and are inbred. These tigers inhabit an isolated region in eastern India and interaction between them and other tiger populations is uncommon. Such populations are vulnerable to extinction even over a short period of time.
The video gained instant traction as Twitter users admired the rarely seen spotted creature.
"Sir, if the population really recovers then it will be a great news for entire state of Odisha," said a Twitter user.
"First time I've seen this..I almost didn't know what cat species it was,'' wrote another.
Another IFS officer, Parveen Kasveen, retweeted the clip and shared additional details on the rare species. "The rare tigers were first officially discovered in STR (Similipal Tiger Reserve) in 2007," he wrote.