Climate change kills aardvarks
Scientists are worried, writes SHEREE BEGA
BY THE time Dr Benjamin Rey encountered the group of starving aardvarks he was studying in the dry, arid Kalahari, they had been reduced to mere skin and bone.
That five of the six mammals eventually starved to death, surprised Rey and his colleagues at Wits University and the University of Pretoria.
But it wasn’t the severe drought that killed them. Rather, hotter temperatures from unfolding climate change wiped out their food and water source: termites and ants.
“It is not because the aardvark’s body can’t take the heat, but that the termites and ants they rely on – not just for food but also for water – can’t take the heat and aridity of changing climates,” said Rey, of the brain function research group at Wits University.
He had fitted “biologgers”, miniature sensors attached to computer chips and implanted into the aardvarks, to six of the animals in the Tswalu Kalahari Reserve.
They were documenting their activity patterns and body temperatures in the Kalahari in 2012 and 2013.
All but one of the study animals – as well as 11 other aardvarks in the area – died because of the severe drought, with air temperatures much higher than normal and very dry soil in the area.
Their deaths are documented in a new study, Drought-induced Starvation of Aardvarks in the Kalahari: An Indirect Effect of Climate Change, published this week in Biology Letters.
It details how semi-arid zones, which aardvarks inhabit, are likely to become hotter and drier with climate change, with increased frequency and duration of droughts.
This will have direct effects on aardvarks through greater heat gain from the environment and increased water requirements.
“We didn’t know there would be a drought in our first year of the study, but we knew that if a drought happened, it might possibly have consequences for the welfare of the aardvark,” said Professor Andrea Fuller, the director of the brain function research group.
“We didn’t anticipate the indirect effects of the drought – that the aardvark’s ant and termite prey wouldn’t cope and that the aardvark would starve as a consequence.”
She said the elusive mammals had tried to save energy by searching for the insects in the daytime as it was warmer, but it wasn’t enough to save them.
The nocturnal animals tried basking in the sun, but it wasn’t enough. Before they perished, their body temperatures had plunged as low as 25°C.
“We’ve shown that aardvarks did not exhibit sufficient physiological plasticity to survive a summer drought in a semi-arid desert,” says the study.
“Despite shifting from a nocturnal to diurnal activity pattern, the aardvarks experienced a progressive decline in body temperature over the dry summer, most until death.”
The experts say aardvarks are highly vulnerable to the warmer and drier climates predicted for the western parts of southern Africa, in the future.
“While unusual now, those are the conditions that climate change is likely to bring as the new normal,” said Fuller.
The animals were between 37kg and 45 kg at the start of the study. “When the aardvarks died they were extremely skinny with prominent ribs, spine and pelvic bones showing.”
The researchers were interested in aardvarks because they play a key role in ecosystems and so little is known about them, said Fuller.
“The aardvark digs the burrows that many other animals, such as warthogs, bateared foxes, African wild cats, ground squirrels, scrub hares, and many birds and reptiles, use as refuges. Most large mammals in southern Africa will not be able to move elsewhere, because of factors like fences, roads, and human settlements. They will only survive if they can stay where they are and adapt.
“Our team is trying to determine if they will be able to adapt sufficiently to cope with climate change.”
The authors noted how the extirpation of aardvarks, which function as physical ecosystem engineers, may disrupt ecosystem stability and result in an undesirable ecological cascade, as seen with digging mammals in Australia.
Fuller said: “We’ve heard reports from other areas, such as in Limpopo, where a number of dead animals were found and we’ve seen photos of very skinny aardvarks in the Karoo.
“People also reported seeing aardvarks in the morning. That is unusual and we think it occurs when aardvark come out to bask in the morning sun to raise their body temperature.
They don’t have sufficient energy to raise their own body temperature by metabolic heat production.”
An aardvark at the Tswalu Kalahari Reserve. They are dying due to unusual temperatures affecting their prey.