Is London getting its own Moo Deng? A potted history of our pygmy hippos

Silent but deadly

They're small and not greatly sociable, but pygmy hippos are one of the most dangerous animals in Africa, responsible for more human deaths than any other animal there except the hippopotamus, lion and elephant. Their habitat is the dense forests and swamps of Liberia, Ivory Coast, Sierra Leone and Guinea, where they spend most of their time submerged, with only their eyes and ears above the water, emerging at dusk to feed on grasses and fruit.

Why do we call them pygmy hippos?

The name pygmy hippopotamus derives from the Ancient Greek words pygmaios "a cubit in height", and hippos, "horse". They are smaller than common hippos and have stockier, rounder bodies, shorter legs and a squarer muzzle. Their eyes, ears and nostrils are all positioned high on their heads to allow them to be almost completely submerged with only their sensory organs above the surface. The largest of the pygmy hippos is about the size of a pony.

There are just two species, the common hippopotamus, which is found south of the Sahara in sub-Saharan Africa, and the pygmy hippopotamus, which is found in the forests and swamps of western Africa.

The pygmy hippopotamus is endangered, with a population of only 2,500 to 3,000 adults remaining in the wild. The main threats to their survival are habitat loss and poaching. The pygmy hippo is classified as an endangered species by the International Union for Conservation of Nature and Natural Resources, due largely to habitat loss and fragmentation.

What's the story behind London's pygmy hippos?

In the 1930s, a pair of pygmy hippos called Guy and Joan were donated by the government of Liberia to Chester Zoo. The couple spent their retirement at Whipsnade Zoo, Bedfordshire. London Zoo acquired its first pygmy hippos in 1962, a pair again: Humphrey and Edwina, both born in Chester Zoo. Edwina went on to give birth to two calves, both male, who were named Bertie and Bill.

In 1993, the London Zoo hippos were moved to Whipsnade Zoo, where they remained until 2006 when, with the opening of the new African Bird Safari at London Zoo, they finally returned to the capital after 43 years.

Don't be fooled by their size

Despite their relatively small size, pygmy hippos are territorial creatures and extremely dangerous, known to attack and even kill humans if they feel threatened. They have sharp teeth and tusks and their bite is incredibly strong. With limited visibility, they can sometimes be unaware of boats approaching and charge them aggressively.

In 2014, a man was killed by a pygmy hippo while trying to take a picture of it with a selfie stick at a zoo in Antwerp, Belgium. The man, who was in his 50s, was reportedly trying to get a close-up of the animal when it suddenly charged at him and bit him on the head. He was rushed to hospital but died from his injuries.

What's next for our London hippos?

There are currently four pygmy hippos at London Zoo: Eric, Susie, Cherry and Blossom. The plan is to move all four to Whipsnade Zoo later this year, where they will join a group of four other pygmy hippos, forming one of the largest groups in the UK.

The move will give the hippos more space to roam and will allow them to form a larger and more cohesive social group. It will also give visitors to Whipsnade Zoo the opportunity to see two groups of pygmy hippos interacting together.