While the stock-taking has scientific integrity, zoo Director David Field said, "We're not just checking how many we've got, but who we've got. That forms the basis of our breeding programs," so the press was invited in to observe and take pictures.
Field said some animals are harder to count than others. A photograph of an aquarium suffices when counting fish, for example, but the endangered partula snails, which are small, well-camouflaged and hide under leaves, must be found and counted by hand.
"They're an incredibly endangered species, so we count each one individually," said Field of the snails. Knowing the precise number we have is crucial."
The more photogenic animals had the most attention Wednesday, the British newspaper The Guardian reported, noting one photographer telling a zoo employee, "Can you move, love, we can't see the meerkats. That's the worst place you can stand."
The meerkats, officially counted as nine, seemed to relish the attention, the newspaper said, but the 59 penguins were described as uncooperative for the cameras, as were the 23 Bolivian squirrel monkeys.
"It's all about charisma," Amy Harris, the Zoo's media manager. "Some animals just have it, and the best way to judge is to look at children's faces when they first see them.
Or count the lenses aimed at the animals, the newspaper suggested.