Biodiversity and Conservation

, Volume 23, Issue 11, pp 2801–2815 | Cite as

Accounting for observation reliability when inferring extinction based on sighting records

  • Ivan Jarić
  • David L. Roberts
Original Paper


Given the current increase in global extinction risk of species, methods that are able to estimate the probability and the time of extinction based on a sighting record of a rare or poorly studied species are becoming increasingly important. One of the major obstacles when using such methods is that many sighting records are burdened with uncertain or controversial observations. What is accepted as a valid sighting can have a substantial effect on resulting predictions. Here we present a simple modification to an existing method that allows for the inclusion of specific sighting reliabilities of individual observations into predictions of the likelihood and the time of extinction. The approach is applied to the sighting records of four presumably extinct bird species. Results indicated that the Ivory-billed Woodpecker (Campephilus principalis) and the Eskimo Curlew (Numenius borealis) may be considered as extinct, even when recent controversial sightings are included in the analysis. The Nukupu`u (Hemignathus lucidus) and O`ahu `Alauahio (Paroreomyza maculata) could potentially still be extant, although with a low probability of persistence. The major advantage of the presented method is that, instead of applying some arbitrary threshold for the sighting reliability that is considered acceptable, it recognizes and incorporates the reliability of each observation into the resulting predictions, by estimating the most likely number of observations and the most likely time of the last observation. Its simplicity facilitates its application for assessments of a larger number species or populations, and makes it accessible as a decision tool.


Extinction probability IUCN Red List Eskimo Curlew Ivory-billed Woodpecker Nukupu`u O`ahu `Alauahio 



We acknowledge the support by the Project No. 173045, funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia. We would like to thank anonymous reviewers for providing helpful comments and suggestions that have improved the quality of the paper.


  1. Burgman MA, Grimson RC, Ferson S (1995) Inferring threat from scientific collections. Conserv Biol 9:923–928CrossRefGoogle Scholar
  2. Butchart SHM, Stattersfield AJ, Brooks TM (2006) Going or gone: defining ‘possibly extinct’ species to give a truer picture of recent extinctions. Bull Br Ornithol Club 126:7–24Google Scholar
  3. Collar NJ (1998) Extinction by assumption; or, the Romeo error on Cebu. Oryx 32(4):239–244CrossRefGoogle Scholar
  4. Elphick CS, Roberts DL, Reed JM (2010) Estimated dates of recent extinctions for North American and Hawaiian birds. Biol Conserv 143(3):617–624CrossRefGoogle Scholar
  5. Fisher DO, Blomberg SP (2011) Correlates of rediscovery and the detectability of extinction in mammals. Proc R Soc Lond B Biol Sci 278(1708):1090–1097CrossRefGoogle Scholar
  6. Fitzpatrick JW, Lammertink M, Luneau MD Jr et al (2005) Ivory-billed Woodpecker (Campephilus principalis) persists in continental North America. Science 308(5727):1460–1462PubMedCrossRefGoogle Scholar
  7. Gotelli NJ, Chao A, Colwell RK, Hwang WH, Graves GR (2012) Specimen-based modeling, stopping rules, and the extinction of the Ivory-Billed Woodpecker. Conserv Biol 26(1):47–56PubMedCrossRefGoogle Scholar
  8. Grogan CS, Boreman J (1998) Estimating the probability that historical populations of fish species are extirpated. N Am J Fish Manag 18:522–529CrossRefGoogle Scholar
  9. Hill GE, Mennill DJ, Rolek BW, Hicks TL, Swiston KA (2006) Evidence suggesting that Ivory-billed Woodpeckers (Campephilus principalis) exist in Florida. Avian Conserv Ecol 1(3):2Google Scholar
  10. IUCN (2001) IUCN Red List Categories and Criteria, Version 3.1. IUCN Species Survival Commission, Gland, Switzerland and Cambridge, UKGoogle Scholar
  11. Jarić I (2014) The use of sighting records to infer species extinctions: comment. Ecology 95(1):238PubMedGoogle Scholar
  12. Jarić I, Ebenhard T (2010) A method for inferring extinction based on sighting records that change in frequency over time. Wildl Biol 16(3):267–275CrossRefGoogle Scholar
  13. Lee TE, McCarthy MA, Wintle BA, Bode M, Roberts DL, Burgman MA (2014) Inferring extinctions from sighting records of variable reliability. J Appl Ecol 51:251–258CrossRefGoogle Scholar
  14. Marshall CR (1990) Confidence intervals on stratigraphic ranges. Paleobiology 16:1–10Google Scholar
  15. McBride MF, Garnett ST, Szabo JK, Burbidge AH, Butchart SHM, Christidis L, Dutson G, Ford HA, Loyn RH, Watson DM, Burgman MA (2012) Structured elicitation of expert judgments for threatened species assessment: a case study on a continental scale using email. Method Ecol Evol 3(5):906–920CrossRefGoogle Scholar
  16. McCarthy MA (1998) Identifying declining and threatened species with museum data. Biol Conserv 83:9–17CrossRefGoogle Scholar
  17. McInerny GJ, Roberts DL, Davy AJ, Cribb PJ (2006) Significance of sighting rate in inferring extinction and threat. Conserv Biol 20:562–567PubMedCrossRefGoogle Scholar
  18. McKelvey KS, Aubry KB, Schwartz MK (2008) Using anecdotal occurrence data for rare or elusive species: the illusion of reality and a call for evidentiary standards. Bioscience 58(6):549–555CrossRefGoogle Scholar
  19. Regan HM, Colyvan M, Burgman MA (2000) A proposal for fuzzy International Union for the Conservation of Nature (IUCN) categories and criteria. Biol Conserv 92:101–108CrossRefGoogle Scholar
  20. Rivadeneira MM, Hunt G, Roy K (2009) The use of sighting records to infer species extinctions: an evaluation of different methods. Ecology 90:1291–1300PubMedCrossRefGoogle Scholar
  21. Robbirt KM, Roberts DL, Hawkins JA (2006) Comparing IUCN and probabilistic assessments of threat: do IUCN red list criteria conflate rarity and threat? Biodivers Conserv 15:1903–1912CrossRefGoogle Scholar
  22. Roberts DL, Kitchener AC (2006) Inferring extinction from biological records: were we too quick to write off Miss Waldron’s Red Colobus Monkey (Piliocolobus badius waldronae)? Biol Conserv 128:285–287CrossRefGoogle Scholar
  23. Roberts DL, Solow AR (2003) When did the dodo become extinct? Nature 426:245PubMedCrossRefGoogle Scholar
  24. Roberts DL, Elphick CS, Reed JM (2010) Identifying anomalous reports of putatively extinct species and why it matters. Conserv Biol 24(1):189–196PubMedCrossRefGoogle Scholar
  25. Rout TM, Heinze D, McCarthy MA (2010) Optimal allocation of conservation resources to species that may be extinct. Conserv Biol 24(4):1111–1118PubMedCrossRefGoogle Scholar
  26. Sibley DA, Bevier LR, Patten MA, Elphick CS (2006) Comment on ‘‘Ivory-billed woodpecker (Campephilus principalis) persists in continental North America”. Science 311:1555aCrossRefGoogle Scholar
  27. Solow AR (1993a) Inferring extinction from sighting data. Ecology 74:962–964CrossRefGoogle Scholar
  28. Solow AR (1993b) Inferring extinction in a declining population. J Math Biol 32:79–82CrossRefGoogle Scholar
  29. Solow AR (2005) Inferring threat from a sighting record. Math Biosci 195:47–55PubMedCrossRefGoogle Scholar
  30. Solow AR, Roberts DL (2003) A nonparametric test for extinction based on a sighting record. Ecology 84:1329–1332CrossRefGoogle Scholar
  31. Solow AR, Kitchener AC, Roberts DL, Birks JD (2006) Rediscovery of the Scottish polecat, Mustela putorius: survival or reintroduction? Biol Conserv 128(4):574–575CrossRefGoogle Scholar
  32. Solow A, Smith W, Burgman M, Rout T, Wintle B, Roberts D (2012) Uncertain sightings and the extinction of the Ivory-Billed Woodpecker. Conserv Biol 26(1):180–184PubMedCrossRefGoogle Scholar
  33. Strauss D, Sadler PM (1989) Classical confidence intervals and Bayesian probability estimates for ends of local taxon ranges. Math Geol 21:411–427CrossRefGoogle Scholar
  34. Thompson CJ, Lee TE, Stone L, McCarthy MA, Burgman MA (2013) Inferring extinction risks from sighting records. J Theor Biol 338:16–22PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Institute for Multidisciplinary ResearchUniversity of BelgradeBelgradeSerbia
  2. 2.Durrell Institute of Conservation & Ecology, School of Anthropology & ConservationUniversity of KentCanterbury, KentUK

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