George Schaller, a young field biologist who volunteered for the trip, went on to become a world-renowned naturalist with the Wildlife Conservation Society.
Dr Narayan and his team of wildlife experts have achieved their success with support from the Durrell Wildlife Conservation Trust (DWCT), a Jersey-based conservation organisation started by naturalist Gerald Durrell.
The late American naturalist Dian Fossey brought their plight to world attention, but it was two researchers working for the Wildlife Conservation Society, Bill Weber and Amy Vedder, who pioneered the idea of using ecotourism as a way to save the animals.