Long-term impacts of abundant perennial water provision for game on herbaceous vegetation in a semi-arid African savanna woodland

Managing surface-water in a large semi-arid savanna park: Effects on grazer distribution patterns

“…If this is not done upfront, managers tend to react to drought cycles by providing additional permanent water sources in waterless areas, aiming to get all forage areas within easy reach for water-dependent herbivores. This ''reactive'' management action often does not consider that the short-term gains resulting from augmenting surface-water will have to be balanced with longer-term losses in terms of starvation-induced mortality (Walker et al 1987), productivity (Parker & Witkowski 1999) and biodiversity (Fensham & Fairfax 2008;James et al 1999). Therefore, in order to recreate and mimic spatio-temporal heterogeneity in surface-water availability, we suggest that permanently operational waterholes, as well as waterholes alternating between being operational and closed should be considered when aiming to protect biodiversity.…”

“…However, since the unexpected decline of the rare antelope ever since about 1986, the artificial waterholes in and around the KNP have been blamed for allowing common grazers' numbers to escalate in certain areas, consequently rising the predation pressure on low-density antelope through the increased prey base (Harrington et al 1999;McLoughlin & OwenSmith 2003;Mills & Funston 2003;Owen-Smith & Mills 2006). Increased artificial waterhole densities were also blamed for degrading the herbaceous layer (Parker & Witkowski 1999), for increasing starvation-induced mortality (Walker et al 1987) and for compromising system resilience due to homogenisation (Grant et al 2002). Consequently the KNP water provision policy was reviewed in 1997 and many artificial waterholes were closed (132 out of a possible 283 reviewed boreholes were recommended for closure; Pienaar et al 1997).…”

Surface water availability and the management of herbivore distributions in an African savanna ecosystem

“…Previous studies have documented that herbivore distributions are influenced by the location of water sources, particularly during the dry season (Western, 1975;Fryxell and Sinclair, 1988;Bergstrom and Skarpe, 1999;Redfern et al, 2003). Additionally, studies have documented increased herbivore impacts on a range of forage and soil variables close to natural perennial, natural ephemeral, and artificial water sources (Parker and Witkowski, 1999;Thrash and Derry, 1999). Studies exploring how herbivore populations are affected by the addition of artificial water sources to an ecosystem suggest that water provision may increase herbivore drought mortality (Walker et al, 1987), increase predation on particular herbivore species (Smuts, 1978;Harrington et al, 1999), and contribute to the decline of rare antelope species (Harrington et al, 1999).…”

The role of water abundance, thermoregulation, perceived predation risk and interference competition in water access by African herbivores

“…The consequences of such aggregations on the vegetation surrounding waterholes have been thoroughly studied (e.g. van Rooyen et al, 1994;Parker & Witkowski, 1999), but very few studies have dealt with the behavioural consequences of such aggregations. High mortality occurs in African herbivores during droughts (Dunham, 1994;Dudley et al, 2001), and the creation of waterholes has led to increases in herbivore populations in many protected areas and game ranches (e.g.…”