Cli­mate change kills aard­varks

Sci­en­tists are wor­ried, writes SHEREE BEGA

Weekend Argus (Saturday Edition) - - FRONT PAGE -

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.

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