Why is the western lowland gorilla extinct?

Once again, the main reason is human beings. Deforestation and sport game hunting in Africa (legal, not many decades ago, and illegal in present days) are other reasons.

Even today there is an African illegal trade of amputated gorilla's hands for use as ashtrays! In 1970, during the King Baudouin visit to the Democratic Republic of Congo, it is known the Belgian king was shocked to see President Mobutu Sese Seko using gorilla's hands as ashtrays in his Presidential Palace.

But the Ebola virus also caused in 2004 the death of hundreds gorilla (Gorilla gorilla) individuals in the Odzala National Park, in Congo.