title: Uncertainty in identifying local extinctions: the distribution of missing data and its effects on biodiversity measures.
abstract: Identifying local extinctions is integral to estimating species richness and geographic range changes and informing extinction risk assessments. However, the species occurrence records underpinning these estimates are frequently compromised by a lack of recorded species absences making it impossible to distinguish between local extinction and lack of survey effort-for a rigorously compiled database of European and Asian Galliformes, approximately 40% of half-degree cells contain records from before but not after 1980. We investigate the distribution of these cells, finding differences between the Palaearctic (forests, low mean human influence index (HII), outside protected areas (PAs)) and Indo-Malaya (grassland, high mean HII, outside PAs). Such cells also occur more in less peaceful countries. We show that different interpretations of these cells can lead to large over/under-estimations of species richness and extent of occurrences, potentially misleading prioritization and extinction risk assessment schemes. To avoid mistakes, local extinctions inferred from sightings records need to account for the history of survey effort in a locality.
authors.affiliation: Centre for Biodiversity and Environment Research, University College London, Gower Street, London WC1E 6BT, UK e.boakes@ucl.ac.uk.
authors.forename: Elizabeth H
authors.identifier: http://orcid.org/0000-0003-3609-4259
authors.initials: EH
authors.lastname: Boakes
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Fuller
authors.affiliation: School of Biology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
authors.forename: Philip J K
authors.initials: PJ
authors.lastname: McGowan
authors.affiliation: Centre for Biodiversity and Environment Research, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Georgina M
authors.initials: GM
authors.lastname: Mace
mesh_terms: D000818:Animals; D001208:Asia; D044822:Biodiversity; D003247:Conservation of Natural Resources; D005060:Europe; D053476:Extinction, Biological; D046094:Galliformes / Q000502:physiology*; D018570:Risk Assessment; D035501:Uncertainty
keywords: biodiversity monitoring; extinction inference; galliformes; local extinction; spatial bias; species occurrence data