How an­i­mal food pyra­mid is af­fected

Weekend Argus (Saturday Edition) - - NEWS - SHEREE BEGA

ZE­BRAS and blue wilde­beest will thrive on shorter grasses, while li­ons, leop­ards and hye­nas will do well too. But long grass feed­ers such as buf­fa­los, tsessebe, reed­bucks and rare roan an­telopes will strug­gle with the drought in the Kruger Na­tional Park.

That’s the ver­dict of Dr Ed­die Riddell, the park’s man­ager of fresh­wa­ter re­sources, who ex­plains in the well-doc­u­mented 1991/92 drought larger preda­tors did well, but this was at the ex­pense of smaller preda­tors in­clud­ing wild dogs, chee­tahs and jack­als who they “out­com­peted” for re­sources.

“Fur­ther­more, the sur­viv­ing buf­falo were the strong­est and most re­silient and thus only the ‘best’ re­pop­u­lated the park,” Riddell writes in the Septem­ber/Oc­to­ber edi­tion of the Wa­ter Re­search Com­mis­sion’s Wa­ter Wheel mag­a­zine.

The ar­ti­cle predicts the un­fold­ing se­vere drought could “hold far-reach­ing con­se­quences” for the Kruger where al­ready the sum­mer rain­falls for last year and this were be­low nor­mal across large parts of the park.

Ex­treme droughts could cause se­vere or longer term ecosys­tem changes, notes the ar­ti­cle.

A com­mon mis­con­cep­tion is that an­i­mals die of thirst dur­ing pro­longed droughts, said Riddell. “In fact, most starve to death af­ter graz­ing has been de­pleted… Some an­i­mal and plant species flour­ish when plenty of wa­ter is pro­vided, oth­ers do not.”

He said the El Nino-re­lated droughts of 1982/83 and 1991/92 were the most se­vere droughts on record in the Kruger, char­ac­terised by be­low nor­mal rain­fall for two con­sec­u­tive years – a sce­nario pre­dicted for this year.

Guide­lines in­clude that wa­ter should not be pro­vided in ar­eas that are nat­u­rally dry.

The catch­ment ar­eas of the five peren­nial rivers that run through the park, in­clud­ing the Lu­vu­vhu, Letaba, Oli­fants, Sa­bie and Croc­o­dile, all orig­i­nate out­side the park.

The ar­ti­cle notes how a se­vere drought ”holds many con­se­quences”. In March 1992, for ex­am­ple, the Sa­bie River, gen­er­ally re­garded as the most bio­di­verse in the coun­try, was close to los­ing its sta­tus as a peren­nial river..

Riddell noted how there’ve been some “chal­lenges” to meet the eco­log­i­cal re­serve in the catch­ments of the Letaba, Croc­o­dile and Sa­bie rivers, but that th­ese have largely been re­solved through col­lab­o­ra­tion with up­stream users.

PIC­TURE: REUTERS

CAR­RION: Vul­tures feed on the car­cass of a gi­raffe.

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