15 May, 06:56 AM
Aletta Harrison, News24
Legend has it that a trigger-happy farmer nearly wiped out one of the last surviving pockets of Cape mountain zebra in the 1970s.
The overzealous hunter allegedly negotiated the rocky mountain roads of the Gamkaberg Nature Reserve near Oudtshoorn in a VW Beetle before it was properly fenced and shot seven zebras in one day. The hides were turned into grain sacks and bridles.
With just six individuals remaining in the newly-established Klein Karoo reserve, and two other isolated pockets in Cradock and Kamanassie, conservationists managed to pull off a remarkable feat – bringing the species back from the brink of extinction.
At the turn of the last century there were thought to be just 60 animals alive. Today there are an estimated 6 000.
Now the success story of how Equus zebra zebra was saved stands alongside that of the bontebok and white rhino as one of the most remarkable accomplishments in South African nature conservation history.
But though the numbers may indicate the Cape mountain zebra has found a sound foothold on its rugged habitat, the future of the species is far more uncertain than it may seem.
Because of the severe drop in numbers, as well as the isolation of remaining populations, the majority of the animals alive today lack the genetic diversity to guarantee the species’ long-term survival.
There is, however, one possible saving grace, and the tiny population at the Gamkaberg holds the key.
There are two major species of zebra that occur in South Africa: The plains zebra, (of which there are two subspecies – the common Burchell’s zebra and the extinct quagga) and mountain zebra, (of which there are also two subspecies – Hartmann’s zebra and the Cape mountain zebra).
Mountain zebras are not as big as plains zebras and live in smaller family groups that are more widely dispersed.
While these zebras were once plentiful on the southern tip of the continent, the arrival of European settlers in the Cape soon decimated their populations.
“They were shot out because they were competing with domestic animals for grazing and their skins were also used for grain bags and bridles and things,” says Gamkaberg Nature Reserve manager Tom Barry.
Barry has been closely monitoring the Gamkaberg zebras for the past 25 years.
He explains this relic population was among those who were adapted to retreat to higher terrain to escape hunters and managed to survive in remote, isolated pockets.
The Cape mountain zebra’s famous cousin – the quagga – was not so lucky.
Three small, fragmented populations remained in the Gamkaberg, Cradock and Kamanassie mountains until conservationists started work to restore the animals to some of their former ranges.
But while the numbers started to indicate the Cape mountain zebra was out of the woods, a study in 2005 revealed that the drastic population decline over the preceding centuries had taken its toll on the gene pool.
‘Super rare, super special’
The study made another, startling discovery that, however, gave a glimmer of hope – the animals at Gamkaberg were the exception, holding precious genetic material not represented in the other two source populations.
Scientists soon realised that these animals had the ability to secure the future of the entire species.
“So it makes the animals that are here at Gamkaberg very special. They are super rare and super special,” says CapeNature mammal ecologist Coral Birss.
“Because they hold a third of the genetic material, it indicates to us that if we mix them with either of the other source populations that we will potentially be able to restore genetic diversity and therefore address some of the associated low genetic diversity manifestations like disease resistance or how their breeding success is affected.”
But disaster struck in 2017 when nature almost finished off the job man started. A fire tore through the Gamkaberg reserve, decimating grazing. The ongoing drought suppressed regrowth and a number of the zebras died as a result. Reserve management was forced to feed the precious survivors – an approach they prefer to avoid.
A mere 25 Gamkaberg zebras are thought to still roam the 40 000ha reserve and the clock is ticking for conservationists.
Room to manoeuvre
While their name might suggest that they live solely in the mountains, a recent study lead by Jessica Lea suggests that the population on the Gamkaberg has been confined to sub-optimal habitat due to past human activities.
“Because the animals in those days retreated into the mountains because they were hunted, people thought that they were only mountain animals… but they do need to go onto the flats at certain times of the year,” Barry explains.
The study suggests allowing for seasonal movement across high- and low-lying habitat types could address the poor breeding rate seen among the Gamkaberg zebras.
CapeNature is now working with partners including the WWF to extend the reserve and an additional 1 000ha of low-lying land has been acquired to improve the quality of habitat available.
“That’s a huge thing because it means that there’s good habitat for another 20 animals. And with that purchase it’s enabled us to really look at a new corridor going further south, so it’s just opened up a lot of new doors,” Barry adds.
While the expansion of reserves may give individual populations the room to thrive, scientists are now hard at work trying to comb through the logistics involved in inter-breeding and translocation to help the species as a whole.
Birss says the first step, however, is to try and get fresh information on the genetic make-up of the Gamkaberg survivors.
“The work on which we base the genetic status is a bit old, so we have identified that we need to update that… and then look at what the mechanisms are that we can implement towards translocation and mixing.”
While there is still a long road ahead, Birss is in no doubt that it’s a worthwhile undertaking for the province and for the country as a whole.
“I think if you look at the landscape in the Western Cape specifically, it’s mostly devoid of large charismatic herbivores, but we have the Cape mountain zebra.
“And the Cape mountain zebra becomes iconic, but it also becomes an indicator of what we’re able to do, but it’s also an umbrella. If you have a large area of land and you use it as an iconic species you know that there’s so much underneath that… that is also protected.
“The number of zebras that you can sustain becomes indicative of how biodiversity is faring overall,” she explains.
“The rate of environmental loss that south Africa experienced in the last 400 years basically stemmed from the Western Cape and this is where we can start turning it around in terms of what we’ve lost in terms of our biodiversity.”