What happens when Rüppel's and Cape Vultures share a cliff?
They make cross-breed babies … well, that is what the reserve manager of the Blouberg Nature Reserve, Mr Johan van Wyk, believes has happened.
A possible Rüppel's x Cape Vulture cross breed was caught on a camera trap at Blouberg's vulture restaurant. Even though it was reported in 2004 that a male Rüppel's and female Cape Vulture at the Blouberg colony had successfully fledged two young in two breeding seasons, an actual hatchling has never been spotted until this year.
The bird has a partial, ivory-coloured bill typical of the adult Rüppel's Vulture, but lacks the prominent 'scaling' typical of the species. "Or is this nature's intervention to inject new diversity into its gene pool? At this stage, we can only wonder and speculate," said Johan.
Historically, Rüppel's Vultures were only found as far south as the northern parts of Tanzania. The first record of a Rüppel's Vulture in South Africa was in June 1994, when vulture guru Gerhard Verdoorn observed a single bird at the vulture colony of the Blouberg Nature Reserve.
A year later, two more Rüppels called Blouberg their home, and a few years later caused eyebrows to raise when a Rüppel's and Cape Vulture were recorded nesting on the cliffs at Blouberg.
After the initial hype died down, the Rüppel's Vulture was spotted no more. It had either left the area or it was there but no one noticed or reported it.
Then, in 2013, a Rüppels was repeatedly photographed by camera traps at a vulture restaurant. The following year, during the annual survey of this colony, the Rüppel's was yet again recorded on the nesting cliffs. Once again, it had paired with a Cape Vulture.
To be sure, DNA testing will have to be done, not only to positively confirm the crossbreed, but also to determine questions such as: What drives this sort of phenomenon; how many crossbreeds are there at Blouberg; and what will the result of this 'foreign' DNA be in the population of a species that is already under threat? "At this stage, we can only wonder and speculate," said Van Wyk.
Local birders are welcome to help document this species by visiting the reserve, which is situated close to Vivo, west of Louis Trichardt. Locally, the Blouberg Nature Reserve is at the forefront of the conservation of vultures and the Cape Vulture, which is on the endangered species' list.