Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) as a potential dispersal agent for fleshy-fruited invasive alien plants: effects of handling behaviour on seed germination

Abstract

The spread of invasive alien plants into natural habitats is of growing global concern. Several studies have investigated the role that avian frugivores play in the dispersal of these seeds and their effects on germination success. Fruit bats have however received little attention as important dispersal agents of invasive alien plants, despite their recognized role as long distance dispersal agents of various native flora. We investigated whether Wahlberg’s epauletted fruit bats, Epomophorus wahlbergi, would positively influence the germination of seeds of invasive alien plants. These fruit bats were fed fruits of four invasive alien plant species—Psidium guajava, Melia azedarach, Eriobotrya japonica, and Morus alba. Epomophorus wahlbergi were able to process more fruit per gram body mass than birds have been observed to do. Spat and de-pulped control seeds had similar germination success and germinated at approximately the same time for most species. While seeds retained in whole fruit had significantly less germination success than spat seeds for all species, except M. azedarach, they mostly germinated at approximately the same time. Epomophorus wahlbergi can swallow small seeds (< 2 mm), while seeds larger than this are generally spat out. Large fruit are usually carried away to feeding roosts where seeds are dropped, thereby dispersing seeds and fruits which are too large for some bird species to ingest. Epomophorus wahlbergi should not be underestimated as dispersers of these invasive alien plants as they consume proportionally large amounts (0.62 ± 0.09 to 0.99 ± 0.11 g.g−1 body mass) of fruit, except for M. azedarach, and positively affect their seed germination rates.