Keepers at London Zoo conducted an annual count of all its animals Thursday, from meerkats to penguins and owls.

Last year's stock-take found the zoo had 17,519 residents but some of the world's most endangered species including Sumatran tigers and a white-naped mangabey have joined since then.

This year's numbers have not yet been released.

The compulsory count, required as part of the ZSL London Zoo's license, will be shared with zoos worldwide by logging the data into the International Species Information System (ISIS), in a bid to boost breeding programmes for endangered animals.

This year's numbers have not yet been released.

"We put all this data together so we know what zoo has what animal," said David Field, the zoo's director.

"All the work we do here counting the animals is so we can understand what we have and breed together the most genetically important male and females together to breed these incredibly endangered species.

Other new residents of the zoo include waxy tree frogs, two new Galapagos tortoises, black and white colobus monkeys and cotton top tamarins, potentially bringing the total number of mammals up from last year's 500.

London Zoo opened in 1828 by the Zoological Society of London, whose early fellows included Charles Darwin.

It first opened to paying visitors in 1847.

The zoo currently has over 650 species, 112 of which are listed as threatened.