Gorilla tries to attack visitor by smashing into glass window at Nebraska Zoo - video

The animals are vegetarians and usually non-territorial

A large silverback gorilla has been captured on camera running and leaping at a man directly behind a window in his zoo enclosure.

The male appears to try to intimidate the visitor by beating his chest and hitting the glass with his back feet as he launches his full weight towards him.

Oblivious to the animal taking a run-up at full speed behind him, a tourist is shown standing calmly in front of the camera.

The visitor remains blissfully unaware as the gorilla begins a run-up behind him

Gorillas are the largest living primates, with wild males usually weighing up to double that of females at between 135 to 180 kg.

They are usually non-territorial and are herbivorous, living off a diet of leaves, shoots, stems and occasionally fruit.

The gorilla launches himself into the air as the tourist calmly looks at the camera

Gorilla groups in the wild - known as "troops" - tend to have one adult silverback male with adult females making up the bulk of the social structure.

Animal rights organisation Peta UK has frequently raised concerns about keeping animals in captivity.

"In the wild, animals may roam for hundreds of miles, hunt their prey, raise their children, explore, play and enjoy complex social relationships," the organisation says.

"Yet in zoos, their lives are restricted to four walls."

Many zoos claim keeping rarer species such as mountain gorillas in zoos helps conservation efforts and educates the public.