Title:

Foraging behaviour of scatter-hoarding gerbils (Gerbilliscus (Gerbillurus)) influences seed fate and dispersal for key plant species in the Namib Desert

Publication Year:
2025
Abstract:

Hairy-footed gerbils (Gerbilliscus (Gerbillurus) spp.) in the Namib Desert play a dual ecological role as both seed dispersers and predators, a behaviour typical of scatter-hoarding species. The fate of seeds following their removal by these gerbils, whether consumed immediately or dispersed, is influenced by a range of factors, including food availability, seed traits and habitat type. This study investigated how local hairy-footed gerbils contribute to the seed dispersal of three common plant species along the lower Kuiseb River in the central Namib Desert. We monitored the fate of marked seeds of Acanthosicyos horridus, Vachellia erioloba and Faidherbia albida, specifically noting whether they were consumed or cached. In addition, we evaluated the distance and depth of the caches, as well as the cache recovery rates and re-caching events. Our results indicate that gerbils removed and cached a higher proportion of A. horridus seeds (removed = 100%, cached = 60.4%) compared to V. erioloba (removed = 12.1%, cached = 40%) and F. albida (removed = 47.3%, cached = 53.7%). Detailed observations of cached A. horridus seeds showed an average dispersal distance of 35.9 ± 1.6 m and a burial depth of 3.76 ± 0.11 cm, with seeds being moved farther from the source with each re-caching event. The cached seeds provided short-term food benefits, with 84% retrieved within 48 hours and only 1.7% remaining unrecovered after 30 days, although some seeds were re-cached in new locations up to four times. Despite the apparent small proportion of seeds that escape predation following dispersal and burial by hairy-footed gerbils, those that remain may gain a competitive advantage by being deposited in microhabitats conducive to germination and seedling establishment. Keywords: Acanthosicyos horridus, cache recovery rate, Fabaceae, recaching, seed preference, synzoochory.

Publication Title:
African Zoology
Item Type:
Journal Article
Language:
en