Keepers brave cold to gather information to be used as part of worldwide conservation effort

Officials at London zoo today began the mandatory annual count of the zoo's population today, with keepers braving the cold to tot up more than 750 different species.

"We need to know not just how many animals we've got, but also who we've got," the zoological director, David Field, said.

Field said the information would be used as part of a worldwide conservation effort because some of the zoo's animals are critically endangered species.

"Some of the animals are extinct in the wild, like our socorro doves," he explained. "The mountain chicken frogs are going extinct as we speak, and it's so important that we know exactly how many we've got, how many we've bred and who has bred who."

Officials expect the count to last a week, with the total population set to be marginally higher than the 14,567 recorded last year.

However, keepers in charge of the zoo's invertebrate population – 7,510, according to last year's figures – get some respite by not always having to count individuals.

"What we do with ants and some of the invertebrates is that we count colonies," Field said. "Although we have a good estimate of how many are in the colony, there's a little bit of cheating that goes on there."

New exhibits mean some animals will be logged for the first time this week. Recent additions to the zoo's population will be counted with varying degrees of difficulty and caution – newcomers include three Galapagos tortoises, two aardvarks, a pack of coatis and some porcupines.

Two lion cubs, the first born at the zoo in a decade, are among the most prized youngsters.