Skip to main content
Kent Academic Repository

Are extinction opinions extinct?

Lee, Tamsin E., Bowman, Clive, Roberts, David L. (2017) Are extinction opinions extinct? PeerJ, . ISSN 2167-8359. E-ISSN 2167-8359. (doi:10.7717/peerj.3663) (KAR id:62610)


Extinction models vary in the information they require, the simplest considering the rate of certain sightings only. More complicated methods include uncertain sightings and allow for variation in the reliability of uncertain sightings. Generally extinction models require expert opinion, either as a prior belief that a species is extinct, or to establish the quality of a sighting record, or both. Is this subjectivity necessary? We present two models to explore whether the individual quality of sightings, judged by experts, is strongly informative of the probability of extinction: the 'quality breakpoint method' and the `quality as variance method'. For the first method we use the Barbary lion as an exemplar. For the second method we use the Barbary lion, Alaotra grebe, Jamaican petrel and Pohnpei starling as exemplars. The 'quality breakpoint method' uses certain and uncertain sighting records, and the quality of uncertain records, to establish whether a change point in the rate of sightings can be established using a simultaneous Bayesian optimisation with a non-informative prior. For the Barbary lion, there is a change in subjective quality of sightings around 1930. Unexpectedly sighting quality increases after this date. This suggests that including quality scores from experts can lead to irregular effects and may not offer reliable results. As an alternative, we use quality as a measure of variance around the sightings, not a change in quality. This leads to predictions with larger standard deviations, however the results remain consistent across any prior belief of extinction. Nonetheless, replacing actual quality scores with random quality scores showed little difference, inferring that the quality scores from experts are superfluous. Therefore, we deem the expensive process of obtaining pooled expert estimates as unnecessary, and even when used we recommend that sighting data should have minimal input from experts in terms of assessing the sighting quality at a fine scale. Rather, sightings should be classed as certain or uncertain, using a framework that is as independent of human bias as possible.

Item Type: Article
DOI/Identification number: 10.7717/peerj.3663
Uncontrolled keywords: Extinction model, Data quality, Possibly extinct, IUCN Red List, Sighting uncertainty, Panthera leo, Tachybaptus rufolavatus, Pterodroma caribbaea, Aplonis pelzelni
Subjects: Q Science > QA Mathematics (inc Computing science) > QA276 Mathematical statistics
Q Science > QH Natural history > QH541 Ecology
Q Science > QH Natural history > QH75 Conservation (Biology)
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation > DICE (Durrell Institute of Conservation and Ecology)
Depositing User: David Roberts
Date Deposited: 11 Aug 2017 08:16 UTC
Last Modified: 04 Mar 2024 17:27 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

  • Depositors only (login required):

Total unique views for this document in KAR since July 2020. For more details click on the image.