Crafty zookeepers ensured a rare vulture chick had the best possible chance of survival - by taking it away from its nest.
London Zoo wanted to make sure the egg laid by Phil, a critically endangered Rüppell’s griffon vulture, stood the best chance of hatching successfully.
So once Phil laid the egg it was whisked away to an incubator - and switched for a wooden dummy egg.
For the next eight weeks, unsuspecting mum Phil and dad Cuthbert tended the decoy egg, while the real thing was kept at 36.6C and monitored.
To mimic the natural care it would have received in the nest, keepers turned it three times a day, weighing it and tracking its progress, while adjusting the temperature and humidity in the incubator.
But hatching itself is the most perilous moment for a young bird, explains London Zoo keeper and bird specialist, Jessica Fryer.
“As soon as the shell breaks and the chick begins to hatch, the egg’s membrane starts to dry out and this can restrict the vulture chick’s movement”, she said.
“Sometimes a chick won’t survive a hatch if that is left to happen, so it was essential that we were overseeing the entire hatch, intervening as necessary under the guidance of Holly Cale, curator of The Horstmann Trust.”
When he emerged on March 8, fluffy vulture chick Rupert weighed just 123g – the same as a small bar of soap.
After being fed by zookeepers for 5 days, it was time for the switch back.
The wooden egg was removed and Rupert was placed inside the remnants of his eggshell and returned to the nest, ready for its parents to find.
Rupert is now back in its nest, doted on by parents Phil and Cuthbert - and has grown to the size of a small chicken.
This made it the first time in London Zoo’s history, keepers have successfully returned a hand-reared vulture chick to its parents after it was born in an incubator.
For Phil and Cuthbert, Rupert is their second offspring. They welcomed their first chick Egbert into the world in 2023 but it's the first time the two have ever reared a chick from infancy.
When Rupert is around 3.5 months old, the zoo’s veterinary team will send a feather off for DNA testing to determine the bird’s sex.
This milestone for vulture rearing at London Zoo marks a key step forward to boost the population numbers.
Jessica added: “The threats to these vultures are huge, as successive and frequent mass poisonings in Africa are driving several species of African vultures to extinction.
"The Rüppell’s griffon vultures are also subject to similar threats to those facing other African vultures: loss of wild prey, habitat conversion into agro-pastoral systems, and collisions with powerlines."
Details will be shared with conservation zoos worldwide, helping to build skills that can bolster the population of these critically endangered birds.
Zookeepers hope this success can be repeated with the practice of 'double-clutching' - an incubation technique involving the strategic removal of newly-laid eggs to encourage the laying of more eggs.
Jessica added: “The lessons from this brilliant conservation success will benefit the global community of conservation zoos and help to continue the vital work needed to protect this species.”
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