A programme to repopulate the Arabian oryx has been so successful, there are now concerns about whether a Dubai reserve has enough food to support the growing herd.
Oryx conservation grows too successful
DUBAI // Conservationists working to save the Arabian oryx from extinction have seen the size of their herd grow so dramatically they are embarking on a pioneering three-year study to make sure the project does not become a victim of its success.
The species, an antelope native to the UAE, was wiped out in the wild by hunters 40 years ago. But the success of captive breeding projects to reintroduce the oryx led to its status being lowered last month from "endangered" to "vulnerable" on the red list of threatened species issued by the International Union for Conservation of Nature.
Seventy of the animals were introduced to a protected area in Dubai in 1999, with a further 30 added five years later. In the intervening years the herd at the Dubai Desert Conservation Reserve has grown to the current healthy total of 420.
But if the number of animals in a given area increases too much, then the plants in the territory become overgrazed. At that point the animals are in danger of starving to death, which would cause their population to crash.
This has already happened at the Mahazat as-Sayd protected area in west-central Saudi Arabia which, like the Dubai reserve, is fenced in. Large numbers of oryx died there between 1999 and 2008, while many fell while trying to get out of the enclosure to find new pasture.
A report in the Wildlife Middle East newsletter said: "Deaths were due to starvation because of reduced availability, accessibility and quality of food plants in the area."
To reduce the risk of repeating this scenario in Dubai, conservationists are about to start a major project to determine the reserve's "carrying capacity", or how many oryx it can support.
"At the moment we have no idea," said Greg Simkins, the reserve's South African conservation manager. "There is very little information on carrying capacity in the whole Arabian Peninsula.
"In South Africa, for every different type of environment the government has a carrying capacity from an agricultural point of view for how many cattle or sheep there should be in a particular area.
"It's very well established in places like the US and Australia, carrying capacity is well documented, but not much work has been done here - and the animal population is going to plummet if you don't look at it."
To work out the capacity, the team will fence off certain areas so that plants can grow without being grazed. They will measure the plants' rate of growth, which will tell them how much food they produce and enable the team to calculate the daily intake an oryx requires.
"We can then extrapolate it across the whole reserve and work out how many oryx we can support," Mr Simkins added. "The carrying capacity project will probably take two years to gather the data, then you're probably looking at another six months to a year before you are able to publish the results."
The herd experienced a population explosion in the early years of the project as 50 calves were born in 2001 and 60 the following year, but the breeding rate has since slowed down.
"We're not still getting all the females breeding every year and I'm quite happy with that, if we settle in to a natural, sustainable level where the population is staying steady, then that will be perfect.
"But I doubt that will happen, I think the population will slowly increase and then you'll run into problems eventually."
At that point the team would have to decide how to manage the population. Possible solutions include implementing contraceptive methods - such as putting oral contraceptives in their food - or transferring animals to other reserves.
"We'd need somewhere suitable to move them to, whether it's in the UAE or outside. If there are other projects in Arabia that are suitable and are looking for oryx, then we would be happy to donate."
The 225 sq km reserve covers nearly 5 per cent of Dubai's total land area and supports hundreds of species, including rare mammals, reptiles and birds.