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"Male" Vulture Surprises Keepers By Laying An Egg

author

Aliyah Kovner

Science Writer

clockJan 29 2018, 19:04 UTC

Harold and her egg. Photo courtesy of Eagle Heights Wildlife Foundation.

Bald head and piercing stare aside, Harold the griffon vulture is quite an odd bird.

The scavenger made headlines worldwide last week after laying an egg in her enclosure at the Eagle Heights Wildlife Foundation in Kent, England. The noteworthy element is that Harold, a resident of the organization’s sanctuary since it opened its doors 20 years ago, was thought to a male this whole time.

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Unlike many bird species, male and female griffon vultures look completely identical – determining the sex of an individual actually requires a DNA test. When Eagle Heights acquired Harold back in the '90s, they were told (s)he was a male based on the results of one such test, performed on her when she was a chick.

In the ensuing years, no one had cause to suspect otherwise, until last Thursday:

“BREAKING NEWS, Today Eagle Heights staff are FLABAGASTED!!!(sic)” a Facebook post exclaimed. “20 years ago we bought HAROLD our MALE Griffon Vulture only to find this morning that he is actually a SHE and has laid her 1st ever egg!!!"

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A popular fixture of the wildlife park’s birds of prey exhibit, Harold had been housed alongside the other birds in the main mews until last fall, when keepers decided to let her spend the winter cozied up in an aviary. 

Similar to chickens, female vultures will lay unfertilized eggs in the absence of a mate--but only in the right conditions. Jemima Parry-Jones MBE, director of the International Centre for Birds of Prey, told IFLScience: “stressed birds are unlikely to lay either in captivity or in the wild.”

Apparently, the new-found privacy inspired Harold to lay for the very first time.

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After recovering from their initial shock, Eagle Heights now hope to begin captive breeding efforts by finding her a mate.

Harold relaxing in the grass at Eagle Heights. Photo courtesy of Eagle Heights Wildlife Foundation

Contrary to some reports, griffon vultures are not critically endangered. The imposing birds, which reach a wingspan of 9.2 feet (2.8 meters), are found in healthy numbers throughout Europe, Asia, and the Middle East.

“Whether it will stay that way is another matter,” said Parry-Jones. “Wind turbines kill a thousand a year, but work is being done using radar tracking so that turbines can be shut down when birds are migrating. Powerlines [also] both kill through collision and electrocution.”

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Regardless of their current status, captive breeding programs are an excellent way to boost declining bird populations and maintain genetic diversity. If griffon vultures were to become threatened in Europe (they are not native the UK), chicks raised by Harold and her mate could be released into the wild to help replenish numbers. Just one breeding pair can make a significant difference.

“The California Condor, the Mauritius Kestrel and many other species of birds have been reliant on that one pair breeding at the start of the programme,” said Perry-Jones. 

Griffon vultures can live up to 40 years in captivity, so while Harold might be an older mom, Eagle Height are optimistic she has time to raise a few future generations. In the meantime, Harold is basking in the media spotlight, bringing public attention to her species' unique charms. 

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"Vultures sadly have a poor press and suffer from people thinking they are ugly," concluded Parry-Jones. "In fact most are not, they have their own beauty and are stunning in flight. They are also crucially important to the environment."


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