Responses of fruit-feeding butterflies to selective logging in Sabah, Borneo

Abstract

This study investigated the impacts of selective logging on tropical butterflies in lowland dipterocarp rainforest of Sabah, Malaysia (Borneo). Fruit-baited traps were used to survey butterflies in unlogged forest and forest that had been selectively logged 10 - 12 years previously in 1988 and 1989. The study focused on butterflies in the sub-families Satyrinae, Nymphalinae, Morphinae and Charaxinae (Nymphalidae). Traps were set up along four transects on existing paths and trails in unlogged forest (two transects, total length 4 km) and logged forest (two transects; total length 4 km). Traps were hung 1-2 m from the ground at 100 m intervals along transects (total of 80 traps). Traps were operated for 12 days each month. A total of 3996 adult butterflies was recorded from 63 species over a period of one year (October 1999 - September 2000). Most of the butterfly species that were present in unlogged forest were also present in logged forest. There was little difference between habitats in numbers of individuals or numbers of species recorded in Shannon-Wiener, Simpson's or Margalef's diversity indices. These results show that selective logging had little effect on butterfly species diversity 10 — 12 years after logging. There was, however, a significant difference among transects, and transects in logged forest had both lowest and highest species diversity (Shannon-Wiener). These results may be due to differences between transects in the intensity of logging. There was no evidence that selective logging resulted in the loss of butterfly species with more restricted geographical distributions. Dispersal and longevity were investigated in several of the more abundant species. Dispersal and longevity distributions fitted negative exponential functions showing that the study species were dispersing randomly and had a constant rate of survival over time. Dispersal and longevity did not differ between habitats or sexes but did differ between species in relation to body size and subfamily. The maximum distance moved by an individual in this study was 4670 m and the maximum lifespan was 175 days (B. dunya in both cases)