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Published on: April 10, 2026
Spatial and temporal extinction dynamics in a freshwater cetacean.
Samuel T Turvey1, Leigh A Barrett, Tom Hart
1Institute of Zoology, Zoological Society of London, Regent's Park, London, UK. samuel.turvey@ioz.ac.uk
Proceedings. Biological Sciences
|May 21, 2010
Summary
The Yangtze River dolphin (baiji) likely did not experience range collapse before extinction. This challenges the idea that declining mobile species always show range contraction, suggesting other factors may drive extinction risk.
Area of Science:
- Ecology
- Conservation Biology
- Zoology
Background:
- Geographical range contraction is a common indicator of species population decline.
- The Yangtze River dolphin (Lipotes vexillifer) was presumed to have undergone significant range collapse before its extinction.
Purpose of the Study:
- To investigate the range dynamics of the Yangtze River dolphin during its population decline.
- To challenge the prevailing range-collapse model for this species and potentially for other declining mobile species.
Main Methods:
- Analysis of 406 baiji last-sighting records from an interview survey of Yangtze fishing communities.
- Examination of sighting data across the species' historical range in the middle-lower Yangtze drainage.
Main Results:
- Evidence suggests the baiji's population decline was not associated with significant geographical range contraction.
- This lack of range contraction persisted even in the decade preceding the species' probable extinction.
- The baiji exhibited large-scale periodic and seasonal movements across its range.
Conclusions:
- Extinction risk in the baiji was not directly related to evidence of range collapse.
- Range contraction and fragmentation may not be universal characteristics of declining mobile species in connected ecosystems.
- Further research is needed to understand the dynamics of range collapse in different species and environments.
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