In Pictures: Weigh-in time for animals at London Zoo

Squirrel monkeys, owls and camels are among the creatures lined up for the annual weigh-in at ZSL London Zoo.

Keepers are recording the height and weight of more than 20,000 animals to monitor their health and wellbeing.

The details will be added to the Zoological Information Management System, a database shared with zoos all over the world that helps zookeepers compare important information on thousands of endangered species.

Asiatic lioness Arya during the annual weigh-in at ZSL London Zoo
Asiatic lioness Arya plays ball during the annual weigh-in at ZSL London Zoo (Yui Mok/PA)
Keeper Hattie Sire with Owlberta the tawny owl during the annual weigh-in at ZSL London Zoo
Keeper Hattie Sire with Owlberta the tawny owl (Yui Mok/PA)
Keeper Mick Tiley with Noemie the Bactrian camel during the annual weigh-in at ZSL London Zoo
Noemie the Bactrian camel checks keeper Mick Tiley’s work on the weigh-in (Yui Mok/PA)

Zookeepers employ various tactics to entice the animals to stand up and be measured.

Penguins are encouraged to walk over scales as they line up for their morning feed, while fun training activities help persuade squirrel monkeys to pop on to the scales.

Keeper Jessica Courtney-Jones attempts to weigh Humboldt penguins during the annual weigh-in at ZSL London Zoo
Keeper Jessica Courtney-Jones hands out fish to the Humboldt penguins (Yui Mok/PA)
A midwife toad during the annual weigh-in at ZSL London Zoo
A midwife toad takes a peek as it is measured (Yui Mok/PA)

The checks help keepers ensure the animals are healthy, eating well and growing at the rate they should.

Weight is a particularly important indicator of health and wellbeing, and can also help zookeepers detect and monitor pregnancies.

Keeper Charli Ellis with Polly the Galapagos tortoise during the annual weigh-in at ZSL London Zoo
Keeper Charli Ellis tries to get the measure of Polly the Galapagos tortoise (Yui Mok/PA)
Keeper Rowan Swainson with squirrel monkeys during the annual weigh-in at ZSL London Zoo
Keeper Rowan Swainson has his hands full with the squirrel monkeys (Yui Mok/PA)