Because some apes are classified as hominids, and politically some consider them persons many consider this genocide. That legal and political issue is treated in another article on ape genocide.
The facts are, that there are very few breeding populations of the gorilla, bonobo, chimpanzee or orang-utan outside captivity, and all such populations are not only formally classified as endangered species, but in the direct path of human deforestation and development, especially in Indonesia and the Congo. They are also hunted by man, as part of the growing African "bushmeat" trade, which has spread to African cities.