One silverback male and three female mountain gorillas have been killed this week in the Virunga National Park in the eastern Democratic Republic of Congo (DRC).

The bodies were discovered in the southern sector of the park by local rangers. All four mountain gorillas were shot, but it is unclear who killed them and why. Post mortem examinations are currently being carried out.

“We are deeply concerned about this incident which follows more than 20 years of successful collaboration for mountain gorilla conservation,” said Mark Rose, Chief Executive of Fauna & Flora International.

Fauna & Flora International, together with WWF and the African Wildlife Foundation, are part of the International Gorilla Conservation Programme, a partnership that works to ensure the conservation of mountain gorillas and their forest habitat in Rwanda, Uganda and the DRC.

The DRC’s Virunga National Park — bordering Rwanda’s Volcano National Park to the south and Uganda’s Mgahinga National Park — is characterized by largely unspoiled tropical montane forests that are extremely rich in biological diversity.

Despite its protected status, encroachment for farming and settlement, as well as by warring rebel factions, is leading to uncontrolled exploitation of the natural resource base, as well as wildlife poaching.

Earlier this year two silverback male gorillas and a female gorilla were shot dead in the park.

According to WWF, just over 700 mountain gorillas survive in the wild; more than 150 of them in Virunga National Park.

“Just two months ago, we celebrated the increase of the gorilla population in neighbouring Uganda’s Bwindi Impenetrable National Park,” said Dr Kwame Koranteng, Regional Representative of WWF's Eastern Africa Regional Programme Office.

“Seven gorillas killed in seven months is a horrifying statistic and a trend that cannot continue,” he added.

Congolese wildlife authorities, with support from the army, are stepping up patrols within the Virunga National Park to protect the mountain gorilla population. Guard posts are being constructed to provide 24-hour surveillance.