Why monitor butterflies?
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.
Population status of butterflies in Ireland
Established in 2008, the Irish Butterfly Monitoring Scheme has been tracking changes in butterfly populations for 14 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 61% since 2008.
The analysis used to generate the results changed slightly this year, a full explanation of the changes can be found in the Annual Report. Results from 2021 show that no species of butterfly has increased in population size since 2008. Brimstone (Gonepterx rhamni) and Peacock (Aglais io) have remained stable from 2008 to 2021, while the Common Blue (Polyommatus icarus), Small Copper (Lycaena phlaeas), Small Heath (Coenonympha pamphilus), Small Tortoiseshell (Aglais urticae), Wall Brown (Lasiommata megera) and Wood White (Leptidea sp.) all experienced a moderate decline in this time.
Green-veined White (Pieris napi) experienced a strong decline (-87% since 2008) along with Large White (Pieris brassicae), Speckled Wood (Pararge aegeria), Orange-Tip (Anthocharis cardamines), Small White (Pieris rapae), Meadow Brown (Maniola jurtina) and Ringlet (Aphantopus hyperantus).
The other species for which trend data are collected are Dingy Skipper (Erynnis tages),Holly Blue (Celastrina argiolus), Dark-green Fritillary (Argynnis aglaja), Grayling (Hipparchia semele) and Silver-washed Fritillary (Argynnis paphia).
The individual trends can be viewed by clicking on each species name above.
The Irish Butterfly Monitoring Scheme does not generate a sufficient amount of data to monitoring population changes in our more localised and rarer butterfly species.
Contributing to pan-European monitoring
The Irish Butterfly Monitoring Scheme is one of 22 monitoring schemes across Europe that form the European Butterfly Monitoring Scheme. An initiative of Butterfly Conservation Europe and the Centre for Ecology & Hydrology (UK) the partnership brings together data from 10,816 transects walked by 100,000 citizen scientist from 22 different countries. This allows pan-European butterfly trends to be detected and provides the data to enable the European Grassland Butterfly Indicator to be generated.
The European Grassland Butterfly Indicator shows that since 1990 Europe has lost 30% of its grassland butterfly populations.
What does monitoring involve?
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 firstname.lastname@example.org 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