Frugivory by carnivores: Black-backed jackals are key dispersers of seeds of the scented !nara melon in the Namib Desert

Abstract

Carnivorous mammals have been reported to feed on fleshy fruits and disperse seeds, but these interactions are seldom observed and are poorly understood in hyper-arid regions. Scent may play a key role in these interactions, given that most carnivores have sensitive olfactory systems and dichromatic vision. The !nara (Acanthosicyos horridus: Cucurbitaceae) in the Namib Desert produces large (10–20 cm diameter) melons that remain green while undergoing increased volatile emissions with a changing chemical profile as they ripen. Using extensive camera trapping, we found that the fruits are consumed mainly by black-backed jackals (Canis mesomelas) and rarely also by other carnivores such as cape fox (Vulpes chama) and brown hyaena (Hyaena brunnea). We found that scent cues play a crucial role as jackals mainly sought fruits at night and easily located ripe fruits that were experimentally buried beneath the sand to remove visual cues. Seeds retrieved from jackal scat showed improved germination relative to un-ingested seeds. This study highlights the importance of fruit scent in mediating seed dispersal mutualisms involving carnivores.