Ecological characteristics of a threatened snake species, Hoplocephalus bungaroides (Serpentes, Elapidae)

Species with ecological (habitat, dietary) specialization and low reproductive output may be at particular risk from anthropogenic habitat disturbance. We studied growth, reproduction and diet of the threatened broad-headed snake (Hoplocephalus bungaroides), a small nocturnal elapid from sandstone habitats in south-eastern Australia. Our data suggest that the life-history traits and diets of broad-headed snakes contribute to their vulnerability. Rather than searching actively for prey (like most sympatric elapids), broad-headed snakes wait under rocks to ambush prey. In consequence, these snakes feed infrequently, grow slowly, mature late and reproduce infrequently (compared with other sympatric snake species). Because of an ontogenetic shift in food habits, populations of broad-headed snakes require access to high densities of velvet geckos (in rock outcrops) as well as small mammals (in adjacent woodland). The specialized diet, reliance upon two distinctive habitats, low rate of growth, delayed maturation and low reproductive output may have exacerbated the vulnerability of broad-headed snakes to habitat destruction. All of these traits may be due to the species' reliance upon ambush predation rather than active foraging. A broader analysis supports the hypothesis that foraging mode may contribute to endangerment: a disproportionate number of 'threatened' species of Australian elapid snakes rely on ambush predation.