Sumatran tiger cubs and their parents walk around their enclosure at London Zoo in London, January 5, 2015. The annual stock take and animal count, a requirement of London Zoo's license, included additions to the international conservation breeding programme such as the three tiger cubs and Philippine crocodiles. (Photo by Toby Melville/Reuters)

Two six month old Philippine crocodiles, two of six who were the first of their kind to hatch in the UK, during the annual stock take at London Zoo, Monday, January 5, 2015. Caring for more than 750 different species, London Zoo keepers started the New Year with the task of counting every single animal. With three Sumatran tiger cubs adding vital numbers to the European conservation breeding programme, the birth of six critically-endangered Philippine crocodiles and the arrival of nine Humboldt penguin chicks, all of the new additions will be added to the records. (Photo by Kirsty Wigglesworth/AP Photo)

Penguins swim in their pool during the annual stock take at London Zoo, Monday, January 5, 2015. (Photo by Kirsty Wigglesworth/AP Photo)

Bolivian Squirrel Monkeys play with an abacus during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

A Sumatran tiger cub walks around its enclosure at London Zoo in London, January 5, 2015. (Photo by Toby Melville/Reuters)

A Zoo Keeper feeds the Bolivian Squirrel Monkeys during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

Humboldt penguins swim in their pool during the stock take at London Zoo in London, January 5, 2015. (Photo by Toby Melville/Reuters)

A black-capped squirrel monkey sits on an abacus during the stock take at London Zoo in London, January 5, 2015. (Photo by Toby Melville/Reuters)

A keeper poses with a young Philippine crocodile at London Zoo in London, January 5, 2015. (Photo by Toby Melville/Reuters)

Zookeeper Vicky Eyson poses with Humboldt penguins at London Zoo in London, January 5, 2015. (Photo by Toby Melville/Reuters)

Sumatran tiger cubs walk around their enclosure at London Zoo in London, January 5, 2015. (Photo by Toby Melville/Reuters)

A Sumatran Tiger looks at visiting children from it's enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

Flamingoes stand in their enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

A Humboldt penguin swims in it's enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

A Sumatran Tiger walks through it's enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

A Rockhopper penguin swims in it's enclosure during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

Keeper Darren Jordan feeds the llamas and alpacas during the annual stocktake at ZSL London Zoo, Monday, January 5, 2015. (Photo by Kirsty Wigglesworth/AP Photo)

A six month old Philippine crocodile, one of six who were the first of their kind to hatch in the UK, during the annual stock take at London Zoo, Monday, January 5, 2015. (Photo by Kirsty Wigglesworth/AP Photo)

January 5, 2015 – London, UK. Penguins are counted at the London Zoo stocktake today. The annual stocktake is required as part of ZSL London Zoo's license and includes every creature. (Photo by Vickie Flores/London News Pictures/ZUMA Wire)

Lamas and Alpacas are being measured during the annual weight-in ZSL London Zoo onJanuary 5, 2015 in London, England. The height and mass of every animal in the zoo, of which there are over 16,000, is recorded and submitted to the Zoological Information Management System. (Photo by Niklas Halle'N/UPPA/ZUMA Wire)

January 5, 2015 – London, UK. Philipino crocodiles are counted at the London Zoo stocktake today. The annual stocktake is required as part of ZSL London Zoo's license and includes every creature. (Photo by Vickie Flores/London News Pictures/ZUMA Wire)

Penguins stand near their pool during the annual stock take at London Zoo, Monday, January 5, 2015. (Photo by Kirsty Wigglesworth/AP Photo)

A Bolivian Squirrel Monkey sits on a cameramans tripod during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. (Photo by Dan Kitwood/Getty Images)

Bolivian Squirrel Monkeys play with an abacus during the ZSL London Zoo's annual stocktake of animals on January 5, 2015 in London, England. The zoo's annual stocktake requires keepers to check on the numbers of every one of the 800 different animal species, including every invertebrate, bird, fish, mammal, reptile, and amphibian. (Photo by Dan Kitwood/Getty Images)

The annual stocktake took place at London Zoo as part of ZSL London Zoo's licence staff have to count every animal, on January 5, 2015. (Photo by Jeff Moore/Splash News)

A Sumatran tiger plays with a football filled with food during the annual stock take at London Zoo, Monday, January 5, 2015. (Photo by Kirsty Wigglesworth/AP Photo)