Two mountain gorillas pose with a park ranger for a selfie. For this selfie, Ndakazi and Ndeze want to imitate one of the humans who has raised them since they were young. (Photo: Mathieu Shamavu/Courtesy of Virunga National Park)

When Mathieu Shamavu posted a selfie on Facebook earlier this month, he called it "another day at the office."

And, indeed, it would be another day — for a full-time ranger whose "office" happens to be Virunga National Park in eastern Congo.

A UNESCO world heritage site, the sprawling and dizzyingly diverse park is home to a world-famous — and critically endangered — population of mountain gorillas.

Shamavu's job is to keep them safe. But sometimes, they see themselves more as colleagues.

Like when Shamavu struck a pose for that selfie — and the mountain gorillas in his company tried to be just as cool as their human friend.

Their pose may also suggest the gorillas, Ndakazi and Ndeze, are "learning to be human beings," Innocent Mburanumwe, Virunga National Park deputy director, told BBC News.

The female gorillas spent part of their lives at the Senkwekwe Center, a park facility dedicated to helping gorillas in tough times.

And this pair, orphaned by poachers at a young age, have certainly known their share of them. In fact, there are just 1,000 mountain gorillas left in the wild, about a third of them in Virunga National Park.

Established in 1925, Virunga was the first national park in Africa. Since then it hasn't wavered in its mission to protect gorillas, even as the region was embroiled violent conflict. Poachers still linger at the fringe of the park, looking for an opportunity to make more orphans, while enriching themselves.

But somewhere in a space that always seems at the edge of peril, about 600 park rangers have made a deep connection with their charges.

And sometimes, with one very viral selfie — flush with swagger and confidence — a couple of mountain gorillas show the world why it's so worth it.

The gorillas in this selfie want to be just as cool as the man who protects them
A Virunga National Park ranger's selfie with two endangered gorillas goes viral.