| dc.description.abstract | A considerable body of scientific evidence shows that the world is currently suffering a biodiversity crisis driven by anthropogenic factors such as land-use change, environmental pollution and climate change. Our knowledge of this crisis is incomplete, however, particularly when it comes to the most diverse multi-cellular organisms on the planet, the insects. Although there is evidence of decline in the abundance, distribution and biomass of many insect species, recent attempts to extrapolate these to global scales and encourage a policy response have been met with scepticism. More data are required, together with reliable methods to integrate and interpret them. In parallel, evidence-based conservation initiatives are urgently needed to address the biodiversity crisis. Citizen science has great promise for gathering much-needed data on insect trends and for engaging the public in biodiversity conservation. Citizen science has undergone a rapid rise in popularity over the past two decades, increasing the capacity for cost-effective, spatially-extensive biodiversity monitoring, while also raising awareness and commitment to nature conservation among participating members of the public. However, citizen science approaches can also present challenges, such as reductions in data quality, constraints in sampling strategies and in the onward reuse of data. In this thesis, citizen science monitoring of Great Britain’s (GB) moths and butterflies is examined as a case study, assessing some of the benefits and limitations of increased participation and demonstrating applications of citizen science data in determining species trends, drivers of change and estimates of extinction risk. Overall moth abundance has decreased in GB, probably mainly as a result of habitat degradation, while climate change has enabled the range expansion of some species (Chapter 2). Much remains to be learnt about other potential drivers of change, such as chemical pollution and artificial light at night (Chapter 2). I demonstrated the efficacy of citizen science by calculating GB distribution trends for 673 moth species for the first time, finding that 260 species had undergone statistically significant long-term declines compared with 160 that had increased significantly (Chapter 3). The geographical patterns of change were consistent with expected responses to land-use, nutrient enrichment and climatic change (Chapter 3). I also utilised citizen-science derived monitoring data for 485 Lepidoptera species to investigate the impact of insect population variability on the assessment of Red List extinction risk using 10-year trends as specified by the International Union for Conservation of Nature procedure (Chapter 5). I concluded that for these taxa, strict use of 10-year trends produces Red List classifications that are unacceptably biased by the start year (Chapter 5). In Chapter 4, I showed that mass-participation citizen science data obtained using a simple sampling protocol produced comparable estimates of butterfly species abundance to data collected through standardized monitoring undertaken by experienced volunteers. Resulting increases in participation, along with the associated benefits of public engagement and awareness raising, need not have a detrimental impact on the ability to detect abundance trends in common butterfly species. However, citizen science participation may affect the onward use of data, unless this is considered at the outset. I found that despite support in principle for open access to distribution records of butterflies and moths, most citizen scientists were much more cautious in practice, preferring to limit the spatial resolution of records, particularly of threatened species, and restrict commercial reuse of data (Chapter 6). Overall, these results demonstrate the potential for citizen science, involving both expert volunteer naturalists and inexperienced members of the public, to address the global biodiversity knowledge gap through generating meaningful trend estimates for insect species and elucidating the drivers of change. | en_GB |
