At London Zoo, the animals come two by two - and sometimes in fours and sixes as well.

The zoo's annual "stocktaking" took place yesterday, giving keepers a chance to check on the numbers of everything from stick insects to tigers - and even a sex-change meerkat.

It was an essential opportunity to draw breath after a busy 12 months which saw a host of new arrivals, including the first two lion cubs to be born at the zoo for a decade.

Zoological Director David Field said: "It's a hugely important day. Of course we are monitoring the information right throughout the year, but today we make sure that all our figures are correct to make sure we know who is breeding with whom and when."

While the trio of giant Galapagos tortoises had a characteristically slow year, there was excitement in the meerkat enclosure with the birth of Lia and her brother Roo - only for Lia to become Liam five months later when she was found to be a boy.

The dozen meerkats, four lions - including cubs Gabriel and Rudi - and two tigers are just some of the zoo's 259 mammals, and it is home to more than 340 amphibians, 207 reptiles and over 5,500 fish.

And spare a thought for the staff given the task of counting the 7,500 bugs.