Big cats have a range of colours that they can be found in. It is certainly true that their standard colour is more common, but in different parts of their range other colourings might be more helpful. For instance, an Amur tiger that was white may find it easier to creep up on its prey.
On the Malay peninsular, as much as half of the leopards are black, as this gives them an advantage.
In this case, a black tiger was photographed. The animals was not entirely black, but having far wider stripes, its back looks more black with yellow stripes rather than the other way round. Fewer animals are taken out of the wild than in the past, when an animal like this would likely have been caught and sold to a zoo for many times the price that tigers normally fetch – as this tiger will increase visitor numbers.