The impact of bush-rock removal on an endangered snake species, Hoplocephalus bungaroides (Serpentes : Elapidae)

Abstract

We examined the impact of habitat degradation (removal of surface rocks) on an endangered snake species (Hoplocephalus bungaroides, Elapidae) at 23 sites in south-eastern Australia, by quantifying the impact of rock removal on (i) the availability of suitable shelter-sites for the snakes and their major prey species (the velvet gecko, Oedura lesueurii), and (ii) the numbers of snakes and geckos. Our survey showed that both the snakes and the geckos prefer rocks lying on other rocks, rather than on soil, and select rocks of particular sizes. The rocks removed by bush-rock collectors overlap considerably in size (diameter and thickness) and substrate (rock on rock) with those used by broad-headed snakes and velvet geckos. Multivariate path analysis suggests that population densities of broad-headed snakes (as measured by capture rates) may be determined primarily by gecko numbers, which in turn depend upon availability of suitable rocks. In some sites, rock numbers were substantially reduced by anthropogenic disturbance. Thus, our survey data suggest that bush-rock removal has contributed to the endangerment of H. bungaroides.