PHOTOS: London Zoo is doing its annual weigh-in

Each measurement is added to the Zoological Information Management System, a database shared with zoos all over the world, helping zookeepers to compare information about thousands of endangered species.

Mark Habben, the zoo’s zoological manager, said: “We have to know the vital statistics of every animal at the zoo – however big or small.

This information helps us to monitor their health and their diets and, by sharing the information with other zoos and conservationists worldwide, we can use this knowledge to better care for all our animals.

Habben added that “different personalities and temperaments” have to be taken into account when weighing and measuring the animals.

He said zookeepers use different tricks to entice the animals to take part, such as “getting penguins to walk over scales as they line up for their morning feed and hanging breakfast from up high to encourage the lions and tigers to reach up to their full height”.

Habben said keepers also use regular weight checks and waist measurements to “identify pregnant animals, many of which are endangered species that are part of the zoo’s international conservation breeding programmes”.

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