Journal of Tropical Ecology



The importance of figs for frugivores in a South African coastal forest


Bärbel Bleher a1c1, Christina J. Potgieter a2, David N. Johnson  a3 and Katrin Böhning-Gaese  a1
a1 Institut für Biologie II, RWTH Aachen, Aachen, Germany
a2 School of Botany and Zoology, University of Natal, Pietermaritzburg, South Africa
a3 KwaZuluNatal Nature Conservation Service, Pietermaritzburg, South Africa

Abstract

For many tropical forests a tendency for fruit production to fluctuate seasonally has been established, with pronounced peaks of abundance and periods of fruit scarcity during which a few important resources maintain frugivore communities. However, there is a lack of studies in subtropical forests on community phenology and on the identification of important resources. In this study, community-wide fruit availability and its use by the local frugivore community was investigated in the subtropical coastal dry forest of Oribi Gorge Nature Reserve, South Africa over 13 mo from July 1997 to July 1998. Along 19.5 km of phenology trails, 940 individuals of 96 plant species bearing fleshy fruits were monitored twice per month and fruit-eating animals observed. Although some fruit was available all year round richness of both fruiting species and fruit abundance showed a seasonal pattern with peaks at the end of August to beginning of October (i.e. before the rainy season) and March to May (i.e. after the rainy season). Periods of fruit scarcity were found in July and August (i.e. during the long dry season) and in November and December (i.e. during the rainy season). Fruits of 23 plant species were observed being eaten by 18 species of bird and two of monkey. Highest animal numbers were attracted by Ficus thonningii, a species that fruited asynchronously during most of the year and during periods of fruit scarcity, and provided high overall fruit biomass. The importance of this species as a potential keystone resource for the frugivore community is discussed.

(Accepted July 12 2002)


Key Words: frugivore community; fruit availability; fruiting phenology; keystone resources; Oribi Gorge Nature Reserve; resource use.

Correspondence:
c1 Corresponding author. Present address: Institut für Zoologie, Abteilung V - Ökologie, Johannes Gutenberg-Universität Mainz, Becherweg 13, 55099 Mainz, Germany. Email: bleher@oekologie.biologie.uni-mainz.de