Collectors endanger Australia's most threatened snake, the broad-headed snake Hoplocephalus bungaroides

The collection of reptiles for the pet trade is often cited as a potential problem for threatened species, but quantitative data on the effects of this trade on wild populations are lacking. In south-eastern Australia the decline of the threatened broad-headed snake Hoplocephalus bungaroides has been blamed on habitat destruction and the collection of snakes for pets, but there was little evidence to support the latter hypothesis. During 1992-2000 we studied one of the last extant southern populations of broad-headed snakes in Morton National Park, New South Wales, where <600 individuals remain on an isolated plateau. Analysis of 9 years of mark-recapture data reveal that the activities of snake collectors seriously endanger the viability of this species. The study population of H. bungaroides was stable over 1992-1996, but declined dramatically in 1997, coincident with evidence of illegal collecting, possibly stimulated by a government amnesty that allowed pet owners to obtain permits for illegally held reptiles. Survivorship analyses revealed that 85% of adult females disappeared from the population in 1997. There was no such effect on male survivorship, suggesting that snake collectors selectively removed adult females, which are the largest snakes in the population. Humans caused significant damage to fragile rock outcrops in three of the 9 years of the study, and a second bout of habitat disturbance in 1999 coincided with a second decline in the H. bungaroides population. We recommend that locked gates be placed on fire trails to protect existing populations of broad-headed snakes.