Cape Parrot Poicephalus robustus diet in a nutshell: use of indigenous and exotic plants in the Eastern Cape province, South Africa

Abstract

The success of conservation action for a threatened species can be improved by knowledge of its feeding and breeding requirements. The Cape Parrot Poicephalus robustus is a threatened endemic restricted to patches of mistbelt forest in South Africa. Cape Parrots are considered dietary specialists, preferring the kernels of yellowwood Podocarpus/Afrocarpus species, and consuming other species when these are not available. We investigated the diet composition of Cape Parrots in the Amathole region of the Eastern Cape province through targeted and opportunistic observations from 2016 to 2021. We monitored the availability of indigenous and exotic forest fruit over this timeframe and determined whether between-season and within-season differences were significant. We also monitored Cape Parrot presence and diet, weekly, at a pecan tree orchard and collected pecan nuts for compositional analysis. Additionally, we investigated whether Cape Parrots tracked this exotic feeding resource relative to local indigenous fruit abundance and changes in pecan nut composition. Cape Parrots were observed feeding on 36 tree species during this study, of which 61% were exotic. We recorded 24 new tree species (mostly exotics) not previously recorded as eaten by this parrot species. However, most feeding records were of parrots eating indigenous rather than exotic species, excluding the targeted observations of them eating at pecan orchards. Cape Parrots fed on pecans in each season despite the relatively high availability of indigenous forest fruits. Although not significant, Cape Parrots appeared to track changes in pecan nut composition during each season, gathering in the largest numbers when fat levels in the pecans were highest. Cape Parrots appear to be adapting to human-modified habitat based on the observations of annual visits to exotic pecan orchards and the high number of exotic species in their diet. The impact of exotic feeding resources on their health remains to be determined.