|A nice waterhole never did any harm, did it? Sasakwa Dam, Grumeti GR July 2009|
|Grazers love artificial waterholes - the migration reaches Seronera, Nov 2010|
|Lions wait for thirst animals by a waterhole, Selous GR, June 2010|
|Roan Antelope, Mwiba Ranch, Jan 2011. Declines have been related to water provision|
|Elephant near dam, Kruger NP, June 2011 - and look at the invasives on the dam!|
But that's not all artificial waterholes do, they also attract elephants. Now, there's a long running discussion between East and South Africans about elephant impacts (dare we say damage?) in protected areas that I'm not going to go into here. But impacts they certainly do have, especially in areas near waterholes as they're another species that doesn't like to travel far from water if they don't have to. So spreading waterholes across the landscape means elephants can easily get everywhere, especially during the crucial dry season when they are feeding on bushes (grasses during the wet season, remember) and have bigger impacts on the habitat. So providing waterholes for elephants everywhere means the vegetation never gets a chance to recover from browsing impact, and can easily start to cause problems throughout the landscape. So, another thing to be aware of.
|Zebra drinking, Manyara Ranch, Sep 2010. Note how heavily grazed the land is around the dam.|
Now, the last thing you might want to argue with me about, of course, is what happens in a dought? If you don't provide water for the animals, surely they die? And that's true, of course - but it turns out that if you do maintain artificial waterholes everywhere, the animals still die - not of thirst, but of starvation. During a drought there far less food around, especially in areas where everywhere is usually accessible to most animals because there are waterholes everwhere. If there are fewer waterholes and things get tough, animals (even those lazy zebra!) will make the decision to walk further to feed in areas they don't normally go and there'll be enough food to go around. So in a serious droung in the 1980s in southern Africa, one private game reserve with lots of waterholes where studies were made lost nearly 90% of grazing animals, whilst the next door Kruger, with fewer waterholes, only lost 35% of animals. So, no, I don't think waterholes are essentially a good idea, even during drought.
The unifying process at work here, with the lions, the elephants and the drought stress, is a loss of heterogeneity - variability in the landscape. With waterholes everywhere, lion predation risk was the same everywhere, elephant impact is the same everywhere, grazers are the same everywhere. Without artificial waterholes, there are refugia from lions, elephants and heavy grazing that can be used by other species and at other times when needs are greatest. Heterogeneity, as we'll see time and time again, is a key issue in maintaining functioning ecosystems.
|Birds like waterholes too! This is a Black-winged Stilt near Ndutu, NCA. Jan 2011|