At the beginning of this century it is estimated that there was 100,000 wild tigers, today the number is less then 8,000. simply put, tigers are disappearing in the wild. The main threats to tigers are poaching, habitat loss and population fragmentation.

Habitat Loss: Across all of Asia, once vast forests have fallen for timber or conversion to agriculture. Only small islands of forest surrounded by a growing and relatively poor human population are left. As forest space is reduced, the number of animals left in the forest is also reduced, and tigers cannot find the prey they need to survive. As a result, tigers begin to eat the livestock of villagers who live near them. Sometimes tigers even attack humans. People sometimes kill the tigers in order to protect themselves and their livestock.

Another problem created by habitat loss is:
Population Fragmentation.
As human populations move farther into the forest, groups of tigers become separated from each other by villages and farms. This means that tigers in one area can no longer mate with tigers in nearby areas. Instead tigers must breed repeatedly with the same small group of animals. Over time, this inbreeding weakens the gene pool, and tigers are born with birth defects and mutations.

Poaching: Even though it is illegal to kill a tiger, wild tigers are still
being poached today because their bones, whiskers and other body parts
can be sold on the black market for a lot of money. Tiger parts are used
in traditional Chinese medicine because some people believe that tiger
parts have special powers. Forestry and wildlife departments are to
understaffed and under budgeted to be effective against the onslaught of
poachers. while the exact number of tigers being poached is unknown,
some sources have estimated that one tiger a day is being killed in India.