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

Abstract

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.