Keepers measure up monkeys, lions and penguins at zoo weigh-in

Bolivian monkeys at London Zoo

Bolivian black-capped squirrel monkeys are weighed at London Zoo - Credit: ZSL London

The annual weigh-in has taken place at London Zoo with penguins, monkeys and giant tortoises among the animals having their vital statistics recorded.

Ahead of the move to their new Giants of the Galápagos enclosure in October, tortoises Dolly, Polly and Priscilla had their carapaces charted, while aquarist Catherine Dixon dove into the new tank in the Tiny Giants exhibit, to measure the growth of corals rescued from the illegal wildlife trade.

zookeeper Cat Dixon

Cat Dixon measures the coral in the Tiny Giants tank during the annual weigh-in at London Zoo - Credit: ZSL London Zoo

Meanwhile Asiatic lioness Arya, who arrived at ZSL in April as a new mate for male Bhanu, measured her seven metres at full stretch with a giant ruler, before patient keepers encouraged the troop of Bolivian black-capped squirrel monkeys onto the scales by offering them tasty treats. Little Nuka weighed in at just 1.2kg, while Noemie the camel was 752kg, Carl the Humboldt penguin 5.6kg, and Polly the tortoise over 115kg.

Keepers spend hours throughout the year recording the heights and weights of the 20,000 animals in their care to monitor their health and wellbeing. The annual weigh-in is a chance to make sure their information is up-to-date and accurate before adding it to the Zoological Information Management System (ZIMS), a database shared with zoos all over the world.

Asiatic lioness Arya  is measured  at ZSL London Zoo

Asiatic lioness Arya is measured at ZSL London Zoo - Credit: ZSL London Zoo

Animal Manager Angela Ryan says: “Knowing the vital statistics of every animal – from the tallest giraffe to the tiniest ant - helps to ensure they are healthy, eating well, and growing at the rate they should. Weight is an important indicator of health and wellbeing. A growing waistline can also help us to detect and monitor pregnancies, as many of the species are threatened and part of international breeding programmes, including today’s Asiatic lions and big-headed turtles. By sharing information with other zoos and conservationists worldwide, we can use this knowledge to better care for the species we’re striving to protect.” 

Celebrate the August bank holiday with a trip to London Zoo. Book tickets at