Irish Butterfly Monitoring Scheme

Butterflies are good indicators of the health of Ireland’s environment and monitoring their populations provide detailed insights into how insect populations are being impacted by land-use and climate change.  The Irish Butterfly Monitoring Scheme, which monitors butterfly populations on a weekly basis between 1st April and 30th September each year, can detect data on butterfly habitat preferences, changes in flight periods and overall changes in population from year to year.

The Irish Butterfly Monitoring Scheme is a citizen science driven monitoring scheme, and as such is an ideal tool for individuals, community groups and professional land managers to measure change in their local biodiversity.

Established in 2008, the Irish Butterfly Monitoring Scheme has been tracking changes in butterfly populations for 16 years. The multi-species index, which is derived from tracking changes in the populations of the 15 commonest species, shows that overall butterfly populations have declined by 55% since 2008.

The Annual Reports for the Irish Butterfly Monitoring Scheme have been published. Key points from the Irish Butterfly Monitoring Scheme Report include:

• None of our resident species showed a population increase when compared with the baseline year of 2008. The four species showing a strong decline are all species of whites, namely Green-veined White, Large White, Orange-tip and Small White. The strong decline of -82% since 2008 of the Green-veined White is particularly worrying.
• The peak flight curve of butterflies occurred at the same time as 2022 (week 14), however, the peak was much lower in 2023. The peak flight curve may have been impacted by the unusually high levels of rainfall that occurred in July last year.

• 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 the 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.

Participating in this scheme involves establishing a fixed walking route (transect) of between 1 km and 2km in length that is monitored once a week from April to September. The route should be established close to where you live or work to make it convenient for you to complete the counts when the weather is suitable. The transect should be divided into 5-15 smaller sections to form sample units, and the number of butterflies seen  within 2.5 m either side of yourself and 5 m in front (a 5 m3 recording ‘box’) are counted for each section. Counts should be completed between 11:00 and 17:00hrs, when the temperature is at least 13°C and during good weather conditions.

Participation in this scheme involves a considerable time commitment but it generates very high quality data on Irish butterflies. If you would like to get involved please contact butterflies@biodiversityireland.ie and support will be provided to get your transect established.

Watch the video of Jesmond Harding of Butterfly Conservation Ireland explaining in detail what is involved with managing a butterfly monitoring transect

The National Biodiversity Data Centre has produced a suite of resources to support recorders with butterfly recording and to develop identification skills. The different resources can be accessed from the links below.