Starving aardvarks signal climate change
THE hardest part of the three years that Dr Nora Weyer spent following elusive aardvarks in the drought-stricken Kalahari was watching the solitary, nocturnal animals starve to death.
“It was really heartbreaking to see the aardvarks I was observing in the poor condition they were in without being able to interfere, because that’s not what researchers do,” says Weyer, who dedicated her PHD research to investigating the effects of climate change on the secretive, rarely-seen mammals, between 2012 and 2015.
What kept Weyer, who was based at Tswalu, a private reserve in the southern Kalahari at the hottest and driest edge of the aardvark’s distribution, motivated was knowing that her research project was meaningful and would make an impact.
“It showed me how important the research was and to make sure that the research community and broader public learns about this issue, because when I was studying, we didn’t know aardvarks were in trouble,” says Weyer, of the wildlife conservation physiology laboratory at Wits University.
The study she led showed that increasing sightings of aardvarks foraging in the daytime can be a sign of food shortages brought on by drought.
It was published this week in the journal Frontiers in Physiology and confirmed earlier findings by the research team that there are times when the aardvarks switch their feeding to the day, and showed, for the first time, that drought caused that switch.
The paper, published with collaborators from UCT and the University of Pretoria, reveals what a shift from night-time to daytime activity means for the well-being of aardvarks in a warming, drying world.
“We suspected it was drought,” says co-worker Dr Robyn Hetem, “but needed a long-term, comprehensive data set to confirm it really was drought causing this unusual behaviour.”
Using biologgers, the researchers recorded body temperature and activity of aardvarks for three years, with Weyer following 12 adults. Satellite imaging showed how droughts affected vegetation and Weyer was able to connect changes in aardvark behaviour and body temperature to conditions in their environment.
As drought became more severe at Tswalu, situated in an area predicted to become hotter and drier under future climate change, the nocturnal animals emerged more frequently from their burrows in the daytime, lowering their body temperature substantially. But those adjustments were not always enough to ensure survival.
The drought killed the vegetation that fed the aardvarks’ prey: ants and termites. They disappeared, leaving the aardvarks starving. Seven of the study aardvarks perished and several others died, presumably from starvation.
“For such a solitary animal with a low density, it’s a lot,” says Weyer.
“They breed very slowly and only have one young so the population can’t really bounce back very fast. We think it’s very likely that with every drought that happens more aardvarks will perish – and it’s not just the aardvarks.
“As soon as the drought affects the vegetation, so it becomes less, then every animal that somehow depends on the vegetation could be affected.”
Professor Andrea Fuller, co-worker and project leader of the Kalahari Endangered Ecosystem Project, says that 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”.
The researchers warn their results “do not bode well for aardvarks facing climate change, and for the many animal species dependent on aardvark burrows for refuge”.
No other animal on the continent creates as many large underground burrows as the aardvark, classified as a species of least concern.
That is one of the reasons Weyer, now based in Germany at the Secretariat of the Convention on Migratory Species, selected aardvarks for her PHD research.
“They have this ecosystem engineer role. They’re not just relevant as a species for themselves but for so many other animals.”
When abandoned, these large burrows provide important shelter for dozens of species including steenbok, porcupines, bat-eared foxes, spring hares and pangolins.
Aardvarks, she says, are charismatic and “deserve some attention from researchers and the public”.
Tackling climate change is crucial, but there is no quick fix.
“We need more studies by conservationists to better understand how animals can cope with drought and extreme environments such as the Kalahari, which is expected to undergo climate change at a much faster rate than other regions…
“This knowledge should then be included in management decisions for reserves and at a higher political level.”