The effects of forest disturbance and fragmentation on fruit-feeding butterflies in Trinidad

Abstract

This thesis explores the use of tropical butterflies as indicators of forest disturbance, fragmentation and forest recovery. The disturbance level of habitats was found to be characterised by the rate of the fraction of species accumulated, with species in undisturbed habitats accumulating more slowly. Undisturbed habitats, but not more disturbed ones, were found to have a vertically stratified butterfly assemblage between the forest understorey and canopy, and certain species were found to be horizontally stratified from the forest edge. No significant effect of breaks in a forest habitat to the dispersal of certain fruit-feeding butterflies was found, but for species which did not cross breaks, it was not possible to determine whether this was due to low numbers of captures or because breaks acted as barriers to dispersal. Cissia arnaea (Nymphalidae: Satyrinae) was present in significantly greatest abundance in 30 year selectively logged forest, even though canopy openness was not significantly different from that found in 5 year forest. Conversely, Colobura dirce (Nymphalidae: Nymphalinae) was found in greatest abundance in the O and 5 year forest and least abundant in the 30 year forest. It is possible that these species could be used to indicate forest recovery following selective logging. Population size estimates and average residency rates were calculated for Cissia penelope and Morpho peleides from fruit trap data. Community structure in the Cissia genus was explored, and the relationship between local abundance and geographic range size investigated and certain restricted range species were not found to be adversely affected by forest disturbance in Trinidad as expected (Thomas 1991 and Hamer et al. 1997)