July 20, 2017, by Tim Radford
If aardvarks are at risk, other species which depend on their engineering could suffer too.
Image: By Scotto Bear via Wikimedia Commons
When the food source fails, the hunter too is at risk. Africa’s hungry aardvarks offer a lesson in climate hazards.
LONDON, 20 July, 2017 – Hungry aardvarks in sub-Saharan Africa may be putting other species at risk of the effects of a warming climate, researchers believe.
The celebrated aardvark – a nocturnal burrowing anteater beloved of word-gamers and dictionary compilers – could not only be threatened itself by climate change, they say: its fate could also be bad news for the creatures which depend on it..
Although Orycteropus afer or earth-pig is not thought to be at serious risk of extinction, a detailed study of the anteaters in the Kalahari region of southern Africa has produced alarming outcomes.
Biologists report in the Royal Society journal Biology Letters that they planted “biologgers” to record their movement patterns in six adult animals that lived in the semi-arid Kalahari.
The summer was particularly hot and dry, and at the end of it five of the recorded aardvarks were dead. So were 11 other aardvarks in the same patch of territory under study.
“Our results do not bode well for the future of aardvarks facing climate change,” they say. Since aardvarks play a key role in engineering African ecosystems, other species may suffer.
The aardvark is known worldwide, if only because it is always on the first page of any dictionary. But most people have never seen one, and know only that these creatures are committed myrmecophages: that is, they live on a diet of ants and termites.
They burrow to stay clear of the heat of the day, and their burrows then become homes or shelters for other species. According to one study at least 27 vertebrate animals – 21 mammals, two birds, three reptiles and an amphibian – have been observed in old aardvark diggings.
The research tells a story of the kind of stress that might be expected with climate change. Under anaesthetic, the South African scientists implanted sensors that could record body temperature and movement, and trackers that could follow the animals as they searched for food. Then they let them back into the wild. It was 2013.
The thermometer rose, summer rains came late, overall rainfall was low, and a severe drought followed. By the end of the summer, five were dead: the researchers recovered most of their instruments and read the data.
They found that, initially, aardvark body temperatures were consistent at 35.4°C to 37.2°C. As the summer wore on, body temperature declined, reaching, they said “as low as 25°C before death, likely due to starvation.”
Researchers have consistently warned that global warming and consequent climate change offers a threat to the creatures of the wild.
“The extirpation of aardvarks that function as physical ecosystem engineers may disrupt ecosystem stability and result in an undesirable ecological cascade”
Although habitat loss, overhunting and pollution offer the biggest threat, other studies have found that the pattern of warming has begun to disrupt whole ecosystems and that even where species are likely to survive, the number of “local extinctions” – regions that were once rich in particular birds or butterflies but record them no more – is on the increase.
The aardvark study is a confirmation of how this can happen: if one hot dry summer means a loss of prey, then the predator population crashes. If heat and drought become part of regional climate, then hunters migrate, or die.
The aardvark is what ecologists call a “keystone species”: that is, other animals depend on it in some way. “The burrows excavated by aardvarks provide thermal refugia for at least 27 vertebrate species. With climate change, these refugia will become increasingly important for those species to buffer climatic extremes,” the researchers conclude.
“The extirpation of aardvarks that function as physical ecosystem engineers, therefore, may disrupt ecosystem stability and result in an undesirable ecological cascade, as seen with digging mammals in Australia. We may face a similar scenario in African ecosystems.” – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.