When wildlife photographer Andy Rouse was told he would find a family of endangered gorillas high on the mountain, he did not expect to find them this high.
Sitting back in the foliage as if it was a cocktail bar, the mountain gorillas had been gorging on alcoholic sap from fresh bamboo shoots and were looking distinctly the worse for wear.
Some were propping up the bar with a bleary air, while others staggered to their feet obviously hoping the mountain police would not ask them to walk in a straight line.
'It was not exactly Gorillas In The Mist, more like gorillas who were p*****,' said Rouse, 43, who was on his fourth trip to see the animals in the Virunga Mountains of Rwanda, Central Africa.
'I had heard they sometimes get like this, but I had never actually seen it. It was just like any family party when one or two members have a little bit too much to drink.
'The boss of the group, a huge silverback called Kwitonda, and some of the younger males were completely out of it.
'Some were running round cackling to each other, others were going mad swinging through the trees, some were just lying on the ground in an inebriated state.
'Normally, they eat handfuls of other vegetation, like a sort of salad to soak up the sap, but this time they were just enjoying a drink.'
The bam-boozled family lives between 8,000 and 13,000 ft up the mountain and are some of the 380 gorillas still living in Rwanda, an area made famous after Dian Fossey's conservation work there.
The book and film, Gorillas In The Mist, told how the animals were threatened by loss of habitat, poachers and disease. Miss Fossey was murdered by poachers in 1985.
To protect the gorillas, photographers and safari groups are not allowed to go within 21ft of them.
Mr Rouse said: 'I was allowed to stay with them for only an hour each day and it was difficult taking photographs of them at their party because I was laughing so much. It was hilarious.'
As these remarkable pictures show, 30-stone Kwitonda could hold his liquor - up to a point.
'When I went back the next day, it was all very quiet, as if they were nursing gorilla-sized hangovers.'
Story and pics here.