Monitoring butterflies in Finnish agricultural landscapes

• What is the status of butterflies in Finland?
• Monitoring method
• Monitoring sites
• Trends in butterfly abundances 1999-2008
• Observed butterfly and moth species
• Basic figures about the monitoring scheme
• Further information

What is the status of butterflies in Finland?

Modern agricultural practices have drastically reduced the areas of meadows and semi-natural grasslands, which are most important habitats for butterflies. Many of the Finnish butterfly species have declined respectively.

Changes in the abundances of butterfly species need to be monitored in order to focus the conservation measures to the most relevant species. In 1999 Finnish Environment Institute started to construct a butterfly monitoring network in the southern half of Finland. By 2008 this network included 55 sites counted by volunteers and 12 sites by professionals.

Monitoring method

Butterflies are monitored with the widely used transect walking method, which was originally developed in the Great Britain by E. Pollard. Today it is also used for butterfly monitoring in several other EU-countries, such as the Netherlands, Belgium, Germany and Catalonia in Spain.

Butterflies are recorded from a 5x5 meter area ahead of the observer. The butterfly count is conducted repeatedly during the summer along the same walking route, which is also kept constant from year to year. 

In Finland the suggested mininum number of annual counts has been seven, conducted once a fortnight from mid-May to late August. Weekly counts are recommended, and done on ca. half of the transects.  However, due to our northern location the butterfly season is typically no longer than ca. 16 weeks, and in the northernmost transects less than ten.

Monitoring sites

During 1999-2008 butterflies have been recorded on a total of 86 voluntary transects. Their number has varied annually between 30 and 55. Locations of the transects in 2008 are shown below. The map also includes the 12 "MYTVAS" -research transects which have been counted annually by professionals since 2001.

Trends in butterfly abundances 1999-2008

Population changes have been estimated for 51 Finnish butterfly species with TRIM software (TRends and Indeces for Monitoring, CBS Netherlands). Monitoring results have been reported annually in the Baptria -magazine published by the Finnish Lepidopterological Society (in Finnish with English abstract). 

Population trends of individual grassland butterfly species are presented in the web site www.biodiversity.fi (direct access here).

The two graphs below present some general trends derived  from the individual species indeces. Summers of 2000, 2002 and 2006 were most favourable for butterflies in the monitoring period. Most  butterfly species declined considerably during the last two summers, which were rather cold and rainy. This may have largely caused the observed predominantly negative population trends in butterflies over this 10-year period. 

Observed butterfly and moth species

A total of  80 butterfly species and 464 747 individuals have been recorded during the monitoring period. On every third transect also day-active moths have been recorded along with butterflies, with a total of 298 moth species and 92 641 individuals observed. All butterfly species and 50 most numerously observed moth species have been listed in the attachments below.

• Butterfly species in transects 1999-2008 (PDF, 10 kb)
• Moth species in transects 1999-2008 (PDF, 7 kb)

Basic figures about the monitoring scheme

First for the years of 2008 and 2007, then the average for the whole monitoring period of 1999-2008.

Further information

Janne Heliola, tel. +358-40-0148654, firstname.surname@ymparisto.fi, Mikko Kuussaari, +358-40-5256249, firstname.surname@ymparisto.fi