Weighing and measuring the animals is a chance for keepers to check on their well-being and diets. Vital statistics from the London Zoo’s weigh-in will be entered into a database, the Zoological Information Management System, and shared with zoos around the world.
How do you get an emperor scorpion to hop up onto a scale to check its weight?
Or get a yawning Asiatic lioness to stand still for a minute so you can take her measurements?
At the ZSL London Zoo, they do it very carefully — with patience, scales and bribes.
Mark Habben, head of zoological management at the Zoological Society of London (ZSL), said in a phone interview Friday that 70 keepers had the zoo’s annual weigh-in the day before.
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Armed with giant rulers and big (and little) scales, along with the animals’ favorite food, they are measuring, weighing and counting most of the 750 species in the care of the zoo.
Because the zoo has about 20,000 animals, he said, “This will go on for the next couple of weeks.”
The keepers are taking the vital statistics of the smallest primates (the pygmy marmosets), the towering creatures (the giraffes) and the many animals in between: gorillas, squirrel monkeys, penguins and ants, to name a few.
How do you get a scorpion on the scale? Apparently by first dropping it in a plastic container. To measure a lion, you dangle something — meat — to tempt it to reach high into the air.
The goal of all this weighing and measuring is to gauge the animals’ health and to make sure “we care for our animals by feeding them the correct food,” the society says on its website.
With such information, one may learn at another zoo, for instance, that a corn snake named Sausage can eat one mouse every 10 days. That’s the same amount that Ebeneezer, a royal python, swallows — except every 21 days. As for Frodo and Freda, White’s tree frogs, it’s 20 crickets every three days.
The annual weigh-in at the London Zoo also lets the keepers figure out if any of the animals are pregnant, Habben said.
The information collected will be entered into a database, the Zoological Information Management System, and shared with zoos around the world to compare important data on endangered species.
The lightest creature weighed at the London Zoo so far is the leaf-cutter ant, whose weight is measured in micrograms, Habben said.
That insect came in at 5 micrograms on average.
The giraffe was the heaviest to weigh, he said. For that, the zoo uses a “specially built” scale.
In the case of a giraffe named Elisa, whose exact weight is no one’s business but her own, it can be revealed that she weighs between 800 and 850 kilograms, or about 1,764 to 1,874 pounds.
The zoo periodically takes the measure of some animals on a monthly basis, but the annual weigh-in is more expansive. For strategic reasons, the keepers begin at a set point, often at feeding time.
According to the Zoological Society of London, which works on the worldwide conservation of animals and their habitats, in addition to operating two zoos:
“A range of techniques are used, from training the sea lions to hold their flippers up to be measured, to tempting the brightly feathered macaw and the scaly python onto the weigh board with some of their favorite treats.”
In this weigh-in, Habben said, the zoo is prioritizing newborns. The penguins, for instance, “had quite a productive breeding season this year,” he said.
Keepers also are homing in on some important species. “We try to go at the key species to correlate dietary changes, growth,” he said.
A penguin named Heathcliff came in at 4.25 kilograms, about 9.4 pounds; and the Pygmy goats, Bramble, Polly and Ellie, tipped the scales at 21.5 kg, about 47 pounds, 19.7 kg, about 43 pounds, and 15.8 kg, or about 35 pounds.
You would think that, given its height and weight, the giraffe would be the hardest animal to weigh. But you would be wrong.
A giraffe does need “an extremely large set of scales,” and must be maneuvered onto platforms, Habben said.
But when it comes down to which animal is the trickiest to weigh, he said, laughing, “The fish are pretty difficult, as you can imagine.”
So the zoo doesn’t bother: “We just measure and count them.”
There are also the aptly named squirrel monkeys. For one thing, they are spread across 16 large enclosures. And some have had babies: two to be precise.
And for another, they live up to their names.
“You’ll have eight or nine of them trying to jump on the scales,” he said. “They’re more interested in playing. They’re pretty cheeky.”
The weigh-ins are taking place during visiting hours, he said.
Friday was an especially good day to be at the London Zoo. It was an opportunity for visitors to gawk — but pretend everything was normal.
There’s a goat — stepping on a scale.
And that gorilla? It’s sidling up to a giant measuring board.
Nothing to see here. Nothing much at all.