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For the first time, a gorilla in the wild has been seen using tools - using a stick to capture and then eat ants.

Previously the behaviour had only been seen in chimpanzees.

Researchers were observing one of eight mountain gorilla groups habituated to humans in the Volcanoes National Park, in Rwanda.

Lisanga, a juvenile female, using a stick to catch and then eat ants - the first time the behaviour has been seen in the wild.

The use of the stick was witnessed by Dr Jean-Felix Kinani, the head veterinarian with Gorilla Doctors, an organisation of vets that works with wildlife authorities to monitor the health of wild gorillas in the area.

'This is the first time tool use has been reported in a wild mountain gorilla despite the intensive monitoring of this subspecies,' the team say.

'A routine health check, including behavioral observations, was performed by one veterinarian and two trackers on May 14, 2013 (the end of the main rainy season) in the Neoboutonia Forest at 7389 feet (2252 m.) altitude, the researchers wrote.

'During the 2 hr monitoring visit, Kigoma, the second ranking silverback, was observed to use his left hand to collect driver ants (Dorylus sp.) from a hole in the ground. 

'When he first inserted his hand into the hole, he quickly withdrew it and ran from the hole while shaking his left arm, presumably to remove the biting ants.'

However, one of the females in the group, called Lisanga, witnessed the event - and it gave her an idea. 

'Lisanga, a juvenile female, was approximately 6m away from Kigoma at this time and observed him eating the ants and running away. 

'She then approached the hole and watched the ants entering and exiting the hole for approximately 2 min. 

Lisanga approached the hole and watched the ants entering and exiting the hole for approximately 2 min.

She then put her left hand into the hole, but quickly withdrew her hand covered in ants, shaking her arm vigorously, again presumably due to painful ant bites.

'She proceeded to insert her left hand into the hole, but quickly withdrew her hand covered in ants, shaking her arm vigorously, again presumably due to painful ant bites.' 

She was then observed to select a piece of wood off the ground that was approximately 20 cm long and 2 cm wide at one end, 1 cm wide at the other. 

The piece of wood was a freshly broken branch, thought to be from a tree found 2 m from the ant hole. 

She inserted the stick into the hole and then withdrew the stick, licking the ants off of the stick. 

'After licking the ants off the stick, Lisanga ran away shaking her left hand to remove the still biting ants.'

The team say no other gorillas appeared to have witnessed Lisanga using the stick nor were any other gorillas observed trying to eat ants during this observation period.'

She then finds a stick, inserts the stick into the hole and then withdrew the stick, licking the ants off of the stick.

Lisanga is a curious gorilla,' explained Dr Kinani to the BBC. 

'She is known to have an investigative personality.'

For example, one anecdotal report details her showing more than casual interest in a researcher's bag, quietly approaching behind the researcher and attempting to take the bag away.