Latest trends from the Butterfly and Bumblebee Monitoring Schemes

The Annual Reports for the All-Ireland Bumblebee Monitoring Scheme and the Irish Butterfly Monitoring Scheme have been published.

Both monitoring schemes are citizen science schemes that track population and phenology (flight) trends in Irish bumblebees and butterflies, detecting the impacts of factors such as land use and climate change on populations. For butterflies, it involves walking a fixed route (transect) on a weekly basis from April to September, when weather conditions are favourable. For bumblebees, the fixed route (transect) is walked once a month from March until October. In both schemes, the number of the different species spotted along different sections of each transect are recorded. These records are the basic data upon which the analysis is carried out.

Key points from the Irish Butterfly Monitoring Scheme Report

  • Long-term trend remains that our common butterflies are still declining. Results from multi-species index  highlight that there was a moderate decline (-57%) in the population of butterflies in 2022 when compared to the baseline year of 2008 (pictured right).
  • None of our resident species showed a population increase when compared with the baseline year of 2008. The common species of whites (Wood White, Green Veined White, Small White and Large White) and browns (Wall Brown, Meadow Brown, Speckled Wood and Ringlet) are showing declines in populations with the Brimstone and Holly Blue the only species showing a stable trend in the timeframe.
  • The flight periods of butterflies were two weeks earlier compared to previous years. This may have been impacted by the warm weather and low rainfall as 2022, according to Met Eireann’s Annual Climate Statement, was the ‘warmest year on record’.
  • The data collected in the Five Visit Monitoring Scheme (a reduced effort monitoring scheme) is now included in the analysis of the full Irish Butterfly Monitoring Scheme. Combining the data from the FVMS and IBMS allows us to generate more accurate trends and will improve the quality of our results.

Can you help? The number of transects walked for the Irish Butterfly Monitoring Scheme is reducing each year, so we are always looking for volunteers to participate. If you would like to establish a transect and walk on a minimum of five visits to help monitor butterflies, please get in touch.

 

The multi-species index derived from the amalgamation of the population trends of 8 common species of bumblebee from 2012 to 2022

Key points from the All-Ireland Bumblebee Monitoring Scheme Report

  • The current overall trend from 2012-2022 is a year-on-year decline of 3.3% (down from 4.1% last year). As expected, with the addition of more data each year, the estimates are improving, and as a result overall loss figures are reducing slightly. The trends do still indicate that bumblebees remain in a precarious position, but there is some evidence that things may be starting to stabilise.
  • Currently, the data flags two species that are showing worrying losses. The Common Carder Bee (Bombus pascuorum) has traditionally been one of our most common bumblebees. Things have improved slightly for the species since 2020, but it is still in moderate decline. Unfortunately, the Large Carder Bee (Bombus muscorum) remains in strong decline. This species is listed as Vulnerable in the 2014 European Bee Red List. Ireland is currently one of its strongholds within Europe, making our trends all the more concerning.
  • The Tree Bumblebee (Bombus hypnorum) is our most recent bumblebee arrival, being first recorded from the island of Ireland in Autumn 2017. It was recorded in the monitoring scheme for the first time in 2021. In 2022, it was picked up in low numbers on three transects in Northern Ireland. This species has been moving northwards in Europe as a result of climate change. We are in a unique position, as we are the only country to have an established monitoring scheme in place before its arrival, and can track its expansion in coming years.

Can you help? In 2022, a record ninety transects were walked at least 6 times from March-October. This is an incredible achievement, and we thank all our volunteers. Our aim is to consistently reach 100 transects each year. We are always looking for new volunteers to participate. If you would like to establish a  monthly bumblebee transect, please get in touch.