Insect population trends and the IUCN Red List process

A - Papers appearing in refereed journals

Fox, R., Harrower, C.A., Bell, J. R., Shortall, C. R., Middlebrook, I. and Wilson, R.J. 2018. Insect population trends and the IUCN Red List process. Journal of Insect Conservation. pp. 1-10.

AuthorsFox, R., Harrower, C.A., Bell, J. R., Shortall, C. R., Middlebrook, I. and Wilson, R.J.

Reliable assessment of extinction risk is a key factor in the preparation of Red Lists and in prioritizing biodiversity conservation. Temporal population trends can provide important evidence for such assessments, but imperfect sampling (observation errors) and short-term stochastic variation in population levels caused by environmental variability (process errors) can reduce the reliability of trends and lead to incorrect quantification of extinction risk. The assessment of insect taxa is likely to be particularly prone to these problems, due to the highly dynamic nature of many insect populations, driven by short life-cycles and sensitivity to environmental factors such as the weather. Using long-term United Kingdom monitoring data for 54 butterfly and 431 macro-moth species, we demonstrate the impact of insect population variability on the assessment of extinction risk using the International Union for Conservation of Nature (IUCN) Red List Criterion A (reduction in population size over the last 10 years). For both taxa, varying the start year of the 10-year population trend had a substantial effect on whether particular species met Red List thresholds and on the overall number of species assessed as threatened. We conclude that for these insect taxa strict application of the 10-year rule produces Red List classifications that are unacceptably biased by the start year. Use of long-term trends with adjustment based on species performance over the last decade may offer a pragmatic solution to this problem. We call for further IUCN guidance for practitioners undertaking Red List assessments of taxa with populations that have high temporal variability.

KeywordsExtinction risk; Threatened species; Biodiversity conservation; Monitoring; Butterflies; Moths
Year of Publication2018
JournalJournal of Insect Conservation
Journal citationpp. 1-10
Digital Object Identifier (DOI)
Web address (URL)
Open accessPublished as ‘gold’ (paid) open access
Publisher's version
Output statusE-publication ahead of print
Publication dates
Online19 Dec 2018
Publication process dates
Accepted10 Dec 2018
Copyright licenseCC BY

Permalink -

217 total views
69 total downloads
3 views this month
4 downloads this month
Download files as zip