Slow life history leaves endangered snake vulnerable to illegal collecting

Chris J Jolly,Brenton Von Takach,Jonathan K Webb

doi:10.1038/s41598-021-84745-1

Chris J Jolly, Brenton Von Takach + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-84745-1

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Abstract

Global wildlife trade is a multibillion-dollar industry and a significant driver of vertebrate extinction risk. Yet, few studies have quantified the impact of wild harvesting for the illicit pet trade on populations. Long-lived species, by virtue of their slow life history characteristics, may be unable to sustain even low levels of collecting. Here, we assessed the impact of illegal collecting on populations of endangered broad-headed snakes (Hoplocephalus bungaroides) at gated (protected) and ungated (unprotected) sites. Because broad-headed snakes are long-lived, grow slowly and reproduce infrequently, populations are likely vulnerable to increases in adult mortality. Long-term data revealed that annual survival rates of snakes were significantly lower in the ungated population than the gated population, consistent with the hypothesis of human removal of snakes for the pet trade. Population viability analysis showed that the ungated population has a strongly negative population growth rate and is only prevented from ultimate extinction by dispersal of small numbers of individuals from the gated population. Sensitivity analyses showed that the removal of a small number of adult females was sufficient to impose negative population growth and suggests that threatened species with slow life histories are likely to be especially vulnerable to illegal collecting.

Highlights

The global wildlife trade is a multibillion-dollar industry that is a significant driver of vertebrate extinction risk[1,2]
While the number of species pushed towards extinction by illegal poaching is increasing[9], few studies have quantified the impact that the removal of wild-caught animals for the pet trade has on wild populations (e.g.10–12)
Our results provide strong evidence that human collection of endangered broad-headed snakes from wild populations to supply the illegal pet trade can drive rapid population declines

Summary

Introduction

Global wildlife trade is a multibillion-dollar industry and a significant driver of vertebrate extinction risk. One notable exception is the threatened broad-headed snake (Hoplocephalus bungaroides) (IUCN status: Vulnerable; Australian Commonwealth status: Vulnerable; NSW status: Endangered), a species endemic to the Sydney region of south-eastern Australia, which has been extensively studied over the last few decades (e.g.28,30–33). This spectacularly coloured venomous elapid snake is highly valued by reptile k eepers[31], and the underground trade in broad-headed snakes is thought to have contributed to its d ecline[34]. The life history traits mentioned above may make this threatened species susceptible to illegal collecting for the pet t rade[31,32]

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