Conducted by the conservation group Endangered Species International, the investigation helps expose the extent of gorilla poaching in the country. The group began its investigation by going undercover, talking to sellers and traders at food markets in Pointe Noire, the second largest city in the Republic of Congo.

Over the course of a year, investigators visited the markets twice a month, recording the amount of bushmeat for sale. "Gorilla meat is sold pre-cut and smoked for about $6 per ‘hand-sized’ piece. Actual gorilla hands are also available," says Mr Pierre Fidenci, president of Endangered Species International (ESI). "Over time we got the confidence of the sellers and traders. They gave us the origin of the gorilla meat and it all comes from a single region."

The team then undertook an expedition to travel to the source of this meat, a forested area called Kouilou, which lies along the Kouilou River around 100 to 130km from Pointe Noire.  Using the same boats that ferry the gorilla meat downriver to the city, the investigators traveled upstream, taking photographs and recording interviews with villagers which revealed the extent of the gorilla poaching.

"According to interviews and field surveys, we think we may have about 200 gorillas left in the area," says Mr Fidenci. "But we estimate that 4% of the population is being killed each month, or 50% in a year. It is a lot." The poachers particularly target adult gorillas of reproductive age which carry the most meat.