The Mountain Gorilla
Narrated by David Niven

Mountain Gorillas are an endangered species that live in high altitude impenetrable rainforests. In this documentary of one man's successful struggle to protect one small population of mountain gorillas on the slopes of Mount Kahuzi in Zaire. The mans name is Adrien Deschryver. It took him four years of daily contact and study to persuade the gorillas to let him approach closely. During that time he was charged many times by the senior males and, in particular, a great silver-backed male whom he calls Kasimir.

https://en.wikipedia.org/wiki/Mountain_gorilla