New Delhi, May 26 -- A guide called out to endangered golden monkeys with grunts and clicks to signal he posed no threat, a familiar sound in the mist-covered forests of Rwanda 's Volcanoes National Park.

Here in one of Africa's most well-known parks, steep ridges and dense vegetation often obscure even the largest mountain gorillas - also endangered - and scientists are turning to new technology to detect and protect them.

Known as environmental DNA, or eDNA, the technology allows researchers to identify species using genetic material like fur or feces left in soil and water. This reduces the impact of human interaction during wildlife surveys that can leave researchers groping through the mist.

The technology, more often used in mari...