Habitat Selection by African Buffalo (Syncerus caffer) in Response to Landscape-Level Fluctuations in Water Availability on Two Temporal Scales

Abstract

Seasonal fluctuations in water availability cause predictable changes in the profitability of habitats in tropical ecosystems, and animals evolve adaptive behavioural and spatial responses to these fluctuations. However, stochastic changes in the distribution and abundance of surface water between years can alter resource availability at a landscape scale, causing shifts in animal behaviour. In the Okavango Delta, Botswana, a flood-pulsed ecosystem, the volume of water entering the system doubled between 2008 and 2009, creating a sudden change in the landscape. We used African buffalo (Syncerus caffer) to test the hypotheses that seasonal habitat selection would be related to water availability, that increased floodwater levels would decrease forage abundance and affect habitat selection, and that this would decrease buffalo resting time, reduce reproductive success and decrease body condition. Buffalo selected contrasting seasonal habitats, using habitats far from permanent water during the rainy season and seasonally-flooded habitats close to permanent water during the early and late flood seasons. The 2009 water increase reduced forage availability in seasonally-flooded habitats, removing a resource buffer used by the buffalo during the late flood season, when resources were most limited. In response, buffalo used drier habitats in 2009, although there was no significant change in the time spent moving or resting, or daily distance moved. While their reproductive success decreased in 2009, body condition increased. A protracted period of high water levels could prove detrimental to herbivores, especially to smaller-bodied species that require high quality forage. Stochastic annual fluctuations in water levels, predicted to increase as a result of anthropogenically-induced climate change, are likely to have substantial impacts on the functioning of water-driven tropical ecosystems, affecting environmental conditions within protected areas. Buffer zones around critical seasonal resources are essential to allow animals to engage in compensatory behavioural and spatial mechanisms in response to changing environmental conditions.

African wetlands and their seasonal use by wild and domestic herbivores

“…3). Various herbivores such as zebra, buffalo, wildebeest, tsessebe and warthog populations may be resident within the OD favouring woodlands and grasslands during the wet season (on large islands or the mainland) and adjacent floodplains during the dry season (Bonyongo 2004;BartlamBrooks et al 2013;Bennitt et al 2014) (Photo 3), Photo 2 Cattle wading and feeding on dense floating mats of Vossia cuspidata and Oryza longistaminata in the Thamalakane river, Okavango Delta, Botswana (Photo credits, R. Fynn). These deep-flooded zones (Table 1) provide critical reserves of forage for wild and domestic herbivores during the late dry season and during droughts such as in the example of these photos, which were taken at the end of the dry season/early wet season (3rd December 2014) when early rains had failed resulting in grasses in the adjacent woodlands being severely depleted while other zebra and buffalo populations migrate away from the OD into the eastern woodlands (Sianga 2013;Bennitt et al 2014) or to the Makgadikgadi pans for the wet season (Bartlam-Brooks et al 2011).…”

Postrelease monitoring habitat selection by reintroduced burchell's zebra and blue wildebeest in southern Mozambique

“…Seasonal fluctuations in water availability cause changes in the profitability of habitats and the animals must be able to adapt behavioral and spatial responses to these fluctuations (Bennitt, Bonyongo, & Harris, 2014).…”

Adaptive cluster sampling for negatively correlated data

“…10) and their spatial distribution depends on the prevailing climatic condition (Bennitt et al. ). Thus, areas with higher temperatures lose ground water (lakes or rivers) because of evaporation, attracting little or no presence of Buffaloes, that is, the lower the temperature the higher the number of Buffaloes.…”

“…The choice of Buffalo and minimum temperature was motivated by the fact that Buffaloes drink a lot of water (Prins, 1996, pg. 10) and their spatial distribution depends on the prevailing (Bennitt et al, 2014). Thus, areas with higher temperatures lose ground water (lakes or rivers) because of evaporation, attracting little or no presence of Buffaloes, that is, the lower the temperature the higher the number of Buffaloes.…”