Knysna Turacos ( Tauraco corythaix) do not improve seed germination of ingested fruit of some indigenous South African tree species

Abstract

Seed dispersal plays an important role in the persistence, regeneration and maintenance of plant communities. It is therefore not surprising that much attention has been paid to the germination potential of seeds ingested by frugivorous animals. Consequently the aim of this study was to determine what effect ingestion of seeds by Knysna Turacos ( Tauraco corythaix) has on the germination rate and germination percentage of indigenous South African tree species. Fruits from twelve tree species were fed to the Turacos in separate trials and seed retention times were determined as it has been suggested that a longer seed retention time may increase germination rates. At the end of each trial, seeds were extracted from excreta of individual birds and planted in trays containing potting soil. Germination was recorded daily until 14 days of no germination. Knysna Turacos seed retention times were in the range of those obtained by other studies, with Ficus sur seeds having the fastest retention times (12.4 ± 0.8 min) and Celtis africana the slowest (34.6 ± 5.6 min). Seed ingestion by Knysna Turacos did not influence the rate at which seeds germinated in 83% of the tree species, but ingested Ficus lutea and Ficus natalensis seeds germinated significantly sooner than whole fruit seeds. Future studies relating the composition of indigenous forest fruits to food preferences of Knysna Turacos may give insight into their role as potential seed dispersers of indigenous fruiting tree species.