Why aardvark numbers are dwindling in the Kalahari

It is not only livestock that are threatened during multi-year droughts; wildlife, too, can succumb to the stress. Dr Nora Weyer and other researchers at the University of the Witwatersrand have found that aardvarks’ feeding in the daytime during extended drought may be a sign that they are starving.

Why aardvark numbers are dwindling in the Kalahari
Sightings of aardvarks foraging during the day in the Kalahari are becoming more common, and are thought to be a sign of food shortages brought on by drought. Photo: Dr Noya Weyer
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Aardvarks occur across most of sub-Saharan Africa, but very few people have seen one, as they are solitary, active mostly at night, and live in burrows.

They use their spade-like claws to build these burrows and dig up ants and termites on which they feed. However, seeing aardvarks feeding in the day is becoming more common in the drier parts of the region.

While catching sight of an aardvark may be a delight for wildlife enthusiasts, researchers of the Wildlife Conservation Physiology Laboratory at the University of the Witwatersrand (Wits) warn that the aardvarks’ behaviour does not bode well for this secretive animal.

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New research by the Wits team, with collaborators from the University of Cape Town and University of Pretoria, has revealed how the shift from night-time to daytime activity is affecting the well-being of aardvarks in a warming and drying world.

The researchers studied aardvarks living at Tswalu, a reserve in the Kalahari that lies on the edge of the aardvark’s distribution range and provides support and infrastructure for researchers through the Tswalu Foundation. The results have been published in the journal Frontiers in Physiology.

Disappearance of ants and termites
Using biologgers, the researchers recorded the body temperature and activity of aardvarks for three years, during which Dr Nora Weyer followed the animals as part of her doctoral research.

Assisted by satellite imaging that showed how droughts affected the vegetation, Weyer was able to connect changes in aardvark behaviour and body temperature to what was happening in the animals’ environment.

Weyer’s research confirmed earlier findings by the team that there were times when the aardvarks switched their feeding to the day, and showed, for the first time, that drought caused the switch.

“We suspected it was drought,” says co-worker Dr Robyn Hetem, “but we needed a long-term, comprehensive data set to confirm that it really was drought causing this unusual behaviour.”

The Kalahari is arid at the best of times, but the drought killed the vegetation that fed the ants and termites. Most of these insects disappeared, leaving the aardvarks starving.

“It was heartbreaking to watch our aardvarks waste away as they starved,” says Weyer.

By shifting their activity from the cold nights to the warm days during dry winter months, aardvarks can save some of the energy needed to keep their body temperature up. But those energy savings were not enough to see the animals through a particularly severe drought, during which many died.

Effect of climate change
“Aardvarks have coped with the Kalahari’s harsh environment in the past, but it’s getting hotter and drier, and the changes to our climate might be too much for them to bear,” says Weyer.

Prof Andrea Fuller, co-worker and project leader of the Kalahari Endangered Ecosystem Project, stresses the need for broader research.

“Because the Kalahari is such a unique and potentially vulnerable ecosystem, we need to better understand whether its animals can cope with the increasingly dry conditions,” she says.

According to the researchers, the disappearance of aardvarks from the Kalahari would be devastating for other animals in this ecosystem. The aardvarks’ large burrows provide shelters for many other species that cannot dig their own burrows, earning the aardvark the title of ‛ecosystem engineer’.

“Unfortunately, the future looks grim for Kalahari aardvarks and the animals that use their burrows. Tackling climate change is key, but there’s no quick fix,” says Weyer.

What conservationists do know is that any solution will require a much better understanding of the capacities that animals must have to cope with drought. And that means many more long-term, comprehensive studies of physiology and behaviour, like that conducted by Weyer and her colleagues at Tswalu.

Email Dr Nora Weyer of the Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand at [email protected].

To read the full article, visit doi.org.

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