Forage intake rates and foraging efficiency of free-ranging zebra and impala

Abstract

ntake rates and foraging efficiency depend on the anatomic features of the foraging animal and its foraging behaviour. Foraging parameters of Burchell's zebra (Equus burchelli) and Impala (Aepyceros melampus) were collected to determine the intake rate, cropping rate and bite size through observation and bite count methods. Intake rates were 48.76 ± 0.49 g/min and 27.28 ± 0.22 g/min for the zebra and impala, respectively. Bite size and cropping rate for zebra were 1.93 ± 0.04 and 25.92 ± 0.30, respectively. For impala, they were 0.78 ± 0.01 and 35.20 ± 0.16, respectively. The maximum theoretical intake rate for zebra was 100.96 g/min and 77.32 g/min for impala. The foraging efficiency index was higher for impala (1.03) than zebra (0.61). For zebra to achieve a 63% intake satiation, forage biomass with a bite size of 1.65 g/bite was necessary, while for impala, biomass with a bite size of 0.97 g/bite was necessary. Zebra's large intake rates, bite sizes and low foraging efficiency are possibly due to its bulk and unselective foraging. Impala's high foraging efficiency, cropping rate and relatively low intake rate are associated with its relatively selective foraging strategy