The world’s smallest population of mountain gorillas, the eastern gorilla subspecies, is split into two, and scientists have debated whether they could be two separate subspecies.

Just over half live in the Virunga Mountains, a range of extinct volcanoes that border the Democratic Republic of Congo, Rwanda and Uganda. Since the discovery of the mountain gorilla subspecies in 1902, its population has endured years of war, hunting, habitat destruction and disease—threats so severe that the species was once thought to be extinct by the end of the twentieth century.

As their name suggests, mountain gorillas live in the high mountain forests between 8,000 and 13,000 feet. The fur helps them survive in environments where temperatures often drop below freezing.