As the Zoological Society of London (ZSL) marks its 200th anniversary, keepers at London Zoo have begun their annual stocktake, carefully counting every animal in their care. The zoo is home to more than 8,000 animals, ranging from tiny leafcutter ants to some of the world’s most threatened species, including critically endangered Asiatic lions.
ZSL, which manages London Zoo, was founded in 1826 as a science-led conservation charity. Its work focuses on protecting endangered species, restoring natural ecosystems and helping wildlife and people live alongside one another. The yearly animal census is a legal requirement for zoo licensing and also plays an important role in guiding international conservation and breeding programmes.
Every animal at the zoo is logged during the count, allowing keepers to maintain accurate records and monitor population changes. Recent births have helped strengthen several key species. In July 2025, the zoo celebrated a major conservation success when 16 Humboldt penguin chicks hatched in a single breeding season. The species is classified as vulnerable and faces declining numbers in the wild along the coasts of Chile and Peru.
In April, eight Socorro dove chicks were also born at the zoo, marking a significant step in efforts to save the species from extinction. Socorro doves are currently extinct in the wild, with only around 180 individuals remaining worldwide, cared for by fewer than 50 conservation organisations.
The zoo also recorded an increase in the population of Darwin’s frogs, with eight new frogs born last year. This species is classified as critically endangered and is threatened by a deadly fungal disease known as chytrid fungus. Conservationists at ZSL described the births as a major milestone in their international programme to protect the frogs.
Dan Simmonds, head keeper at London Zoo, said the work carried out at the zoo is vital for the future of many endangered animals. He explained that maintaining healthy and sustainable populations is essential, particularly for species that are critically endangered or already extinct in the wild.