Utility of a forage-productivity model for predicting herbivore abundance in the eastern Karroo, South Africa, varies among habitats

Fortier, An De; Landman, Marietjie; Kerley, Graham I. H.

doi:10.1016/j.jaridenv.2014.06.004

Cited by 9 publications

(4 citation statements)

References 27 publications

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“…The 28,000‐ha property is transected by the Melk River and its tributaries and covers diverse landscapes, with karoo plains giving rise to the steep ridges of the Great Escarpment and Southern African Plateau. The reserve lies on sandstones and shales of the Beaufort bedrock group that are extensively intruded by Karoo dolerites (De Fortier, Landman, & Kerley, 2014).…”

Section: Methodsmentioning

confidence: 99%

“…Mean daily temperatures range between 10°C and 27°C. Samara comprises representative areas of four of South Africa's seven biomes, namely Nama Karoo, Grassland, Savanna, and Albany Thicket (De Fortier et al., 2014). Habitat types are distributed in a reasonably predictable pattern, with open karoo‐thicket mosaics along gentle bottom slopes, closed thickets along steep slopes and the ridges at the edge of the plateau, and open grasslands along the plateau.…”

Section: Methodsmentioning

confidence: 99%

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How should a clever baboon choose and move rocks?

2020

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Chacma baboons (Papio ursinus) intentionally overturn rocks to feed on the invertebrates beneath. However, baboons do not move all the rocks they encounter, with this presumably reflecting cost–benefit (or effort–reward) trade‐offs in their foraging behavior. We ask, how do “clever baboons” choose rock sizes and shapes and move these rocks? Using optimal foraging theory, we predicted that baboons would prefer to move medium‐sized rocks, a trade‐off between moving larger rocks that might require more effort to move, and smaller rocks that likely do not provide enough prey (the reward) to make the effort worthwhile. We also expected baboons to prefer rounded rocks as these will require less energy to move by rolling (rather than being flipped as for flat rocks) and that the effort of rock movement might be offset by moving rocks along the shortest axis. We show that baboons have clear preferences for specific rock sizes (medium‐sized) and shapes (angular and flat when these were medium‐sized), and the way in which rocks are moved (along the shortest axis). Prey occurred infrequently under rocks. The low predictability of prey beneath rocks suggests that such prey, when encountered, is of considerable value to baboons for them to expend the search effort, and also explains the extensive nature of rock movement by baboons in the landscape. Our study provides a novel application of the optimal foraging theory concept and has important implications for understanding and predicting how animals choose to move rocks.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

How should a clever baboon choose and move rocks?

2020

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“…The study was conducted at Samara Karoo Reserve (24°50 19.60 E, 32°21 41.67 S), situated in the eastern Karoo of South Africa, approximately 30 km south-east of Graaff-Reinet, in the Eastern Cape. The region is semiarid, receiving 300-400 mm of rainfall per annum (De Fortier et al, 2014), with average temperatures ranging from a mean minimum of 10°C to a mean maximum of 27°C (van Cauter et al, 2005). Within Samara, the Kondoa plateau, an area characterised as Sweet Grassland, dominated by the tussock grasses Eragrostis lehmanniana and Themeda triandra (De Fortier et al, 2014), was selected as the study site.…”

Section: Study Sitementioning

confidence: 99%

“…The region is semiarid, receiving 300-400 mm of rainfall per annum (De Fortier et al, 2014), with average temperatures ranging from a mean minimum of 10°C to a mean maximum of 27°C (van Cauter et al, 2005). Within Samara, the Kondoa plateau, an area characterised as Sweet Grassland, dominated by the tussock grasses Eragrostis lehmanniana and Themeda triandra (De Fortier et al, 2014), was selected as the study site. This area (about 1200 ha) supports a resident population of approximately 40 zebra and 200 wildebeest (A. Feldon, Samara Karoo Reserve, pers.…”

Section: Study Sitementioning

confidence: 99%

Do ruminants and hindgut fermenters differ in their activity? Comparison of syntopic black wildebeest and Cape mountain zebra

Forbes

Kerley

2022

Behav.

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Optimally foraging animals should minimise time spent foraging in order to perform other fitness-enhancing activities. The ruminants’ more efficient digestive system, requiring lower volumes of forage, is predicted to provide an advantage over hindgut fermenters with respect to foraging effort, but this may be offset by their need for higher quality forage. We contrasted the activity of two similarly-sized, syntopic grazers, black wildebeest (Connochaetes gnou), a ruminant, and Cape mountain zebra (Equus zebra zebra), a hindgut fermenter, using camera trap data and tested the volume-requirement and the nutrient-driven hypotheses, seasonally. Zebra and wildebeest activity varied seasonally, potentially due to differences in resource availability. In winter, a greater proportion of wildebeest were recorded grazing relative to zebra, supporting the nutrient-driven hypothesis, whilst the inverse occurred (although not significantly) in summer, supporting the volume-requirement hypothesis. Seasonal variation in resources may provide temporal foraging trade-offs of benefits for ruminants and hindgut fermenters.

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Scared of the dark? Nychthemeral sociality in territorial black wildebeest (Connnochaetes gnou) bulls

Forbes,

Smit,

Kerley

2024

acta ethol

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The degree of prey sociality reflects trade-offs between predation risk, and competition for mates and resources. Consequently, the degree of sociality is predicted to differ spatiotemporally. Variations in nychthemeral sociality are, however, understudied. We assessed the activity of solitary, territorial black wildebeest bulls (Connochaetes gnou) over rutting and non-rutting seasons. We predicted that solitary bulls would reduce their nocturnal use of territorial stands and join herds to reduce predation risk from nocturnally hunting lions (Panthera leo), but that these responses would differ across rutting and non-rutting seasons. We used camera trap data and modelled solitary bull and herd activity over 24-hour daily cycles, across rutting and non-rutting seasons. We calculated the proportion of images with solitary bulls and herds across nocturnal and diurnal periods, across both seasons. We show that solitary bulls are predominantly diurnal across both seasons, but the probability of nocturnal detection is higher in the rutting than in the non-rutting season. Furthermore, we recorded a lower proportion of solitary bulls to herds at night in the non-rutting relative to the rutting season. Thus, wildebeest bulls may trade-off predation risk for mate acquisition during the rutting season but reduce risky solitary behaviour during the non-rutting season.

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Utility of a forage-productivity model for predicting herbivore abundance in the eastern Karroo, South Africa, varies among habitats

Cited by 9 publications

References 27 publications

How should a clever baboon choose and move rocks?

How should a clever baboon choose and move rocks?

Do ruminants and hindgut fermenters differ in their activity? Comparison of syntopic black wildebeest and Cape mountain zebra

Scared of the dark? Nychthemeral sociality in territorial black wildebeest (Connnochaetes gnou) bulls

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