Foraging behaviour of wild impala (Aepyceros melampus) and Burchell's zebra (Equus burchelli) in relation to sward height

Mwasi, Shem M.; Heitkönig, Ignas M.A.; Wieren, Sipke E. Van; Prins, Herbert H.T.


Foraging behaviour plays a key role in the interaction between herbivores and vegetation, their predominant food source. Understanding this interaction is crucial to providing information that is useful for conservation of herbivores. The objective of this study was to determine how sward height influences functional response and movement patterns of free ranging wild impala and zebra at the Kenya Wildlife Service Training Institute. The study was conducted for 3 months. Sward height is an important parameter that indicates how intensive a sward has been grazed and it influences intake rate through its effect on bite size. Bite size, instantaneous intake rate, specific mass intake rate and feeding station interval for impala and zebra increased with sward height. Sward height in combination with an animal's sex was found to have a profound effect on specific mass intake rate in impala. Zebra had a longer feeding station interval and lower stepping rate in tall swards compared to impala. Despite differences in their specific body mass and digestive strategies, impala and zebra maximized their intake rates in tall swards as a trade-off among the swards. Tall swards are therefore critical in the study area and should be protected from bush encroachment which is a persistent problem. 2017 John Wiley & Sons Ltd.