Comparative Responses of Five Arboreal Marsupials to Tropical Forest Fragmentation

Abstract

I used data from 160 spotlighting censuses to compare responses of five species of arboreal marsupial folivores to fragmentation of tropical rainforests in NE Queensland, Australia. Data from 1,062 mammal detections in 1986–1987 revealed a strong gradient in extinction proneness. Most vulnerable were lemuroid ringtail possums (Hemibelideus lemuroides), which declined by >97% in abundance in forest fragments and secondary regrowth. Herbert River ringtail possums (Pseudocheirus herbertensis) and Lumholtz's tree-kangaroos (Dendrolagus lumholtzi) exhibited negative but intermediate responses to fragmentation, whereas coppery brushtail (Trichosurus vulpecula) and green ringtail (P. archeri) possums were least affected, relative to populations in unfragmented rainforest. A multiple-regression model incorporating log₁₀ fragment area and two measures of fragment isolation explained 82% of the variation in arboreal species richness in 10 fragments ranging from 1.4 to 590 ha. “Corridors” of secondary vegetation helped ameliorate effects of fragmentation for some species. The most useful indicator of extinction proneness was the relative abundance of a species in forest regrowth, not its initial rarity in unfragmented rainforest. The ability of these folivores to use regrowth appeared to depend upon their denning requirements, diet, and degree of arboreality.