What makes a species vulnerable to extinction? Comparative life-history traits of two sympatric snakes

Jonathan K. Webb, Barry W. Brook*, Richard Shine

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

115 Citations (Scopus)


Although it is well known that species vary in their vulnerability to extinction, the reasons are poorly understood. Theory predicts that long-lived species with 'slow' life histories (small litters, slow growth, late maturation) should be at greater risk than short-lived species with high potential rates of increase. This hypothesis was tested by comparing life-history traits of two species of sympatric, elapid snakes: the endangered broad-headed snake, Hoplocephalus bungaroides, and common small-eyed snake, Cryptophis nigrescens. From 1992 to 2000 a mark-recapture study of both species was undertaken in Morton National Park, south-eastern Australia, and this information was used to construct transition matrices for each species. The endangered H. bungaroides was found to mature late (6 years of age), had a high juvenile (54.7%) and adult (81.6%) survival rate, and a long generation length (10.4 years). In striking contrast, the common C. nigrescens matured early (within 3 years), had a lower juvenile (30.4%) and adult (74.4%) survival rate (but higher recruitment rate), and a substantially shorter generation length (5.9 years). Elasticity analyses revealed that H. bungaroides was considerably more sensitive to survival past the age of 2 years (68.6%) than C. nigrescens (37.4%). These results provide support for the hypothesis that species with slow life histories are more vulnerable to extinction.

Original languageEnglish
Pages (from-to)59-67
Number of pages9
JournalEcological Research
Issue number1
Publication statusPublished - Jan 2002
Externally publishedYes


  • Cryptophis nigrescens
  • Elasticity
  • Extinction
  • Hoplocephalus bungaroides
  • Life history


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