Bristol Zoo's baby gorilla Kukena holds onto his mother's arm as he ventures out of his enclosure at Bristol Zoo's Gorilla Island on May 4, 2012 in Bristol, England. The seven-month-old western lowland gorilla is starting to find his feet as he learns to walk having been born at the zoo in September. Kukena joins a family of gorillas at the zoo that are part of an international conservation breeding programme for the western lowland gorilla, which is a critically endangered species. (Photo by Matt Cardy)

Competitors dressed in a gorilla outfits prepare ahead of the Great Gorilla Run on September 24, 2011 in London, England. Hundreds of people dressed in gorrilla suits participated in the 7 km run around the City of London which is hoped will raise £400,000 GBP, anabling funding for projects dedicated to the protection and preservation of Gorillas. (Photo by Dan Kitwood/Getty Images)

People look at lighting artist Bruce Munro's latest installation “Field of Light” is seen in the grounds of the Holbourne Musuem on November 23, 2011 in Bath, England. (Photo by Matt Cardy/Getty Images)

A rider demonstrates Lighting artist Bruce Munro latest installation “Star-Turn” at a one-night event in front of the Holburne Museum on December 21, 2011 in Bath, England. (Photo by Matt Cardy/Getty Images)

Undated David Yarrow handout photo of a gorilla as the self-taught wildlife photographer promotes his book, Encounter. (Photo by David Yarrow/Clearview/PA Wire)

A chimp motions for Santa to deliver his gift during Lion Country Safari's annual Christmas with the Chimps on Thursday, December 20, 2012. (Photo by Bruce R. Bennett/The Palm Beach Post)

Gorillas at Royal Burgers’ Zoo, Arnhem, Netherlands, on November 28, 2013. (Photo by Vidi Photo/Startraks Photo New York)