Many insect pollinators are becoming less widespread in Britain and elsewhere and we have limited understanding of the effect of these changes on the pollination services they provide. This is largely due to the lack of long-term, standardised monitoring of their populations.
Current evidence for pollinator declines comes from records of species occurrence submitted by volunteer recorders and managed by national recording schemes and at the Biological Records Centre. These invaluable datasets make it possible to track long-term changes in distributions, but they are relatively unstructured and provide no direct information on abundance, population size or pollination service.
They also tend to be biased towards the places recorders like to visit, or particular species of interest, often containing significant gaps in geographical coverage.
Statistical methods have been derived to generate trends from these long-term, large-scale datasets but systematic structured sampling of insect pollinators would provide more robust measures of status and trends.
Strategies or action plans for pollinators in England, Wales and Scotland, and for Northern Ireland and the Republic of Ireland, have been developed with ambitions to strengthen pollinator monitoring. These include providing much-needed data on the state of our insect pollinators, especially wild bees and hoverflies, and the role they fulfil in supporting farming and other wildlife.
A recent study led by CEH developed and tested a range of potential sampling methods and analytical approaches for long-term monitoring of pollinating insects. This considered the challenges posed by the number of species involved (ca. 550 for UK bees and hoverflies alone), the difficulties of identification to species level, the comparatively small number of volunteer recorders who would be willing to commit to structured surveys and even smaller number of experts to ensure data quality.
The study concluded that there is considerable scope to enhance monitoring of pollinators in the UK through the integration of data from a range of structured and unstructured survey approaches, ensuring a robust evidence-base to inform policy and improve predictions on the effects of future land-use change and other environmental pressures on pollinators from local to national scales.