Butterflies are sensitive to environmental change and recording their numbers provides key information not only about their status, but about the broader health of the environment. Moreover, where conservation work is being carried out, the effects of the management can be assessed. Formal recording is carried out nationally under the UKBMS (UK butterfly monitoring scheme). This partnership, between a variety of organisations, includes Butterfly Conservation, with input from the Wildlife Trusts. Regular recording began in 1976 with over 16 million butterflies counted since then.
Following the Fortunes of Butterflies
Under the UKBMS, butterflies are counted weekly by walking a set route or transect while recording the numbers of each species seen in a “bubble” that extends to the sides and in front of the recorder. The recording season starts on the first of April and finishes at the end of September, continuing for longer if butterflies are still flying. Weather conditions must meet minimum criteria for a count to be valid. Much of the recording is done by volunteers so it is frustrating to encounter cold temperatures or rain at the weekend after fine weather throughout the working week!
Carrying out a butterfly transect each week provides a wonderful opportunity to follow the fate of these beautiful insects throughout their flight period. Over time you can see first-hand how their numbers are changing in a particular place. It also lets you get to know an area especially well, following the fortunes not only of butterflies but of other wildlife too. On our Cole Wood transect on the Blean near Canterbury we have seen this year how coppicing sweet chestnut has allowed butterfly numbers to skyrocket with sightings including Brimstone, Green Hairstreak and Painted Lady in the Spring and White Admiral this Summer. Continued management by Kent Wildlife Trust and other organisations is also vital for the rare Heath Fritillary on the Blean. Regular coppicing is required to maintain cow wheat, the butterfly’s larval food plant. Pleasingly, numbers of Heath Fritillary have been higher on our transects this year than last. Counts on our West Blean West transect are higher than in Cole Wood, but with the recent coppicing in Cole Wood we hope that numbers will increase in this area next year.
While carrying out a weekly transect is a big committment, anyone with 15 minutes to spare can become involved in the Big Butterfly Count underway now until August 9th. See www.bigbutterflycount.org