A dung beetle that feeds on fig: implications for the measurement of species rarity

Abstract

This communication examines fruit feeding behaviour in rain forest dung beetle communities from Sabah, Malaysian Borneo, and looks at divergences within this guild. Special attention is given to fig-feeding behaviour in one species of dung beetle, and to the implications that such specializations have for the measurement of rarity and species diversity in tropical forests. Possible repercussions for the species of tree on whose fruits dung beetles feed are also discussed. Dung beetles exploit ephemeral resources that are patchily distributed through time and space. In most cases, they display generalist coprophagous feeding strategies, although resource specificity has been shown to play an important role in the population ecology of some dung feeding species (Balthasar 1967, Cambefort 1991, Kingston 1977). In tropical rain forests, where mammalian biomass is significantly less than in other areas (i.e. the African savannas - Cambefort & Walter 1991), and dung is therefore more limiting, some dung beetles have adapted to feed on fruit, fungi, carrion and plant detritus (Halffter & Matthews 1966, Hanski 1989a), and the dung of birds and reptiles (Howden & Young 1981, Young 1981). Other rain forest species demonstrate specialization to either omnivore or herbivore dung (Estrada et al. 1993). Differences in feeding strategies within dung beetle communities in tropical forests together represent an important niche-axis through which individual species can diverge from sympatric congeners, and leads to enhanced local species richness.