Gorillas have shown that being a big ape is no excuse for bad table manners – although their eating habits may not put them on a par with polite society they at least have learnt how to use a napkin.

Zoologists observing western lowland gorillas in Gabon have discovered that they use plant leaves to clean their faces and hands after a messy snack.

The gorillas’ favourite fruit, the oily detarium, tends to drip juice over their fur, so after they have had their fill they pick leaves to wipe off the excess. “We were amazed to discover that gorillas use these leaves like napkins, and it clearly demonstrates we still have plenty to learn about these incredible animals,” Noelle Kumpel, of the Zoological Society of London, said.

“They eat these messy fruits – and others – which mess up their faces and their hands and pick leaves to wipe themselves.”

Dr Kumpel described the practice as akin to the use of tools by a variety of primates. “It’s something we haven’t seen before and hasn’t been officially documented,” she said.

Gorillas are happy to choose any leaf that is most convenient, but they prefer the giant marantaceae leaves. Dr Kumpel said: “They are picky about the parts of the plant they eat but will take a leaf to clean themselves at random.”

Animal trackers from the Baka tribe, who work for the zoologists, seek out the discarded leaves to identify the gorillas’ route throught jungle. The marantaceae plant is a source of food for the gorillas, but they prefer the young shoot. When grabbing a napkin they just pick the biggest or closest leaf.

Dr Kumpel said that recognition of the gorillas’ behaviour was an important part of conserving them because it provided insights into their needs and desires. “The more we understand about them, the more we can do to protect them. Habitat loss is one of the greatest threats to gorillas, followed by poaching for the bushmeat trade and disease such as ebola,” she said.

The discovery was made by researchers working at the Zoological Society of London gorilla conservation project at Mikongo Conservation Centre, which is trying to protect gorillas in the Lopé National Park.

Western lowland gorillas are the most numerous of the four subspecies. They are classified as endangered on the red list of the World Conservation Union (IUCN) and threats to their survival include poaching, disease and loss of habitat.

Apart from the after-dinner use of leaves, there is little ceremony to the routine of a gorilla sitting down for a meal. The dominant male does, however, choose the prime spot, much as the master of a house would sit at the head of the table.

Groups of gorillas have a social hierarchy that is led by the dominant male, the silverback. Boisterous youngsters that get too close while he is eating risk being beaten off.

The western lowland gorillas live in tropical and subtropical forests in central African countries including Gabon, Nigeria, Cameroon, the Central African Republic and the Democratic Republic of Congo. The subspecies has a brow that is more pronounced than in other gorillas, and it has a wider skull. It can reach a height when fully grown of 5ft 9in and is unusual in having thumbs that are longer than its fingers. Females weigh up to 300lb (135kg) but males can exceed 600lb.

Animal craft

New Caledonian crows have been found to make tools from twigs and leaves to hook insects from nooks and crannies. They store the tools for later use.

Orcas have learnt to set traps for gulls. They regurgitate food as bait for gulls and lurk beneath the surface. When a gull tries to take the half-digested food the orca swallows the bird.

Chimpanzees rip branches off trees, peel their bark and sharpen the tips with their teeth to use as spears to skewer bushbabies hiding in holes.

Gorillas have been observed using a stick to gauge the depth of water, and placing a trunk over mud to act as a bridge.

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