Resource selection, utilization and seasons influence spatial distribution of ungulates in the western Serengeti National Park

Abstract

Understanding herbivore selection and utilization of vegetation types is fundamental to conservation of multispecies communities. We tested three hypotheses for how ungulate species select their habitats and how this changes with season: first, resources are distributed as a mosaic of patches so that ungulates are also distributed patchily; this distribution reflects habitat selection, which changes with season, the different ungulates behaving differently. Second, resources become scarcer in the dry season relative to those in the wet season. If interspecific competition prevails, then all species should show a contraction of habitats chosen. Third, if predation is limiting, competition will be minimal, and hence, habitat selection by herbivores will not differ between seasons. We used frequencies of occurrence in four common vegetation types in western Serengeti National Park to determine selection coefficients and utilization patterns and Chi‐square analysis to test the hypotheses. The results showed that selection changes differently in each species, agreeing with the first hypothesis. Herbivores did not all become more selective, as predicted by the competition hypothesis, nor did selection remain the same across seasons, as predicted by the predation hypothesis. These results can be useful in constructing habitat suitability maps for ungulate species with special conservation needs.

Reframing the mammoth steppe: Insights from analysis of isotopic niches

“…They are also consistent with seasonal variation in the mechanism of herbivore coexistence, with more niche separation occurring in winter during times of low forage availability. Tooth wear studies have suggested seasonally-based resource partitioning (Rivals et al, 2009Rivals and Lister, 2016), as has been observed for some modern African savannah species (Bukombe et al, 2017;Kleynhans et al, 2011;Prins et al, 2006) and suggested for some Brazilian Pleistocene megaherbivores (Dantas et al, 2017). It is possible that competitive exclusion occurred during winter periods of resource scarcity and that species had overlapping niches during the rest of the year.…”

“…African savannah herbivores exhibit lower dietary and niche separation during seasons of high plant productivity and greater niche separation during the low productivity dry season (Bukombe et al, 2017;Kleynhans et al, 2011;Prins et al, 2006). Experimental removal studies of herbivores in the African savannah did not observe complete functional redundancy between species, but there was functional redundancy for some response variables, such as vegetation height (Goheen et al, 2013;Pringle et al, 2014;van der Plas et al, 2016).…”

“…Vegetation-mediated predation risk is a factor controlling what niche space is used by savannah herbivores (Anderson et al, 2016;Barnier et al, 2014;Bukombe et al, 2017;Hopcraft et al, 2012;Sinclair, 1985). This can lead to habitat overlap between herbivore species as a predatoravoidance strategy (Sinclair, 1985), as well as to changes in herbivore diet (Barnier et al, 2014).…”

Large mammals and wetland utilisation: A case study in Yankari Game Reserve, Nigeria

“…Water, food and cover are important factors influencing distribution of animals (Afolayan, Milligan, & Salami, ), and wetlands offer these basic necessities. Threat of dehydration, starvation and mortality in the dry season can cause movements from upland areas of dried and depleted forage to wetland buffer zone (Fynn et al, ; Girma, Mamo, & Ersado, ; Jenkins, Corti, Fanning, & Roettcher, ; Macandza, Owen‐Smith, & Cain, ; Owen‐Smith, ; Stacie, Erek, Nabil, Dhaval, & Bruce, ; Yaba, Mekonen, Bekele, & Malcolm, ), suggesting that wetlands are important for sustaining herbivore nutrition over the dry seasons (Bukombe et al, ; Grant & Scholes, ; Hopcraft, Olff, & Sinclair, ; Parrini & Owen‐Smith, ) and influencing their assemblages across wetlands. Wetlands also enable mammals to achieve thermoregulation via bathing pools and mud wallows.…”

Habitat use by a mixed feeder: impalaAepyceros melampusin a heterogeneous protected area

“…The impala prefers open habitats (Estes 1991, Fritz & Bourgarel 2013), avoiding dense woodlands (Bukombe et al . 2017) and tall unburnt grasslands (Rduch 2016), as an anti-predator strategy (Anderson et al . 2010).…”