The Potential of Foraging Chacma Baboons (Papio ursinus) to Disperse Seeds of Alien and Invasive Plant Species in the Amathole Forest in Hogsback in the Eastern Cape Province, South Africa

Abstract

The invasion of alien and invasive plants into the threatened Amathole Forest in Hogsback, Eastern Cape Province (South Africa) is an emerging priority conservation issue. The objective of this pilot study was to document and compare the foraging visits of two chacma baboon (Papio ursinus) troops in their natural and human habitats and their foraging behavioural activities to understand their potential to disperse ingested alien seeds in Hogsback. We also estimated the number of seeds per faecal sample collected from the foraging trails of the two troops of baboons, and determined potential dispersal distances using allometric equations. Since the focal troops used preferred sleeping and foraging sites, we predicted that these sites would have a high concentration of propagules. We applied the normalised difference vegetation index (NDVI) to discern possible vegetation cover changes. Overall, the two chacma baboon troops showed a similar number of daily foraging visits, although they preferred to forage more in human-modified than natural habitats. Their feeding and moving activities were significantly greater than other activities recorded during the study. There were significant differences in the numbers of seeds of six different fruiting plant species: 82.2 ± 13.3% (n = 284) for Acacia mearnsii; 78.9 ± 12.1% (n = 231) for Pinus patula, and 64.0 ± 20.0% (n = 108) for Solanum mauritianum. The two baboon troops could transport about 445 536 seeds from the six focal fruiting plant species considered in this study. Baboons’ seed dispersal distances were long at > 5 km per daily foraging activity. The NVDI vegetation cover analysis (i.e., 1978–2023) shows that the dense vegetation cover expanded by 80.9 ha, while the moderate and sparse vegetation cover collectively decreased by 10.3 ha. Although the seed dispersal pattern was neither clumped nor displayed any recognisable pattern, against our prediction, the number of faecal samples containing alien seeds and the observed foraging movement patterns suggest that chacma baboons disperse alien plant seeds that may establish and facilitate the deterioration of the natural forest. Further quantitative studies investigating the diversity of the plant species dispersed, their germination rates after ingestion by baboons, and their seasonal patterns are required to understand the baboon seed dispersal systems in the Amathole forests of Hogsback.