This summer’s appalling weather, with its low temperatures, heavy rainfall and strong winds, may well be causing problems for many of our butterflies. Temperature can influence the time that it takes for a butterfly larva or pupa to develop, or reduce the activity of adults that need to find a mate or lay eggs. Of course, there is still much of the summer to go and we might find that as the weather picks up so do our butterflies.
The impression that you get of just how well a particular species is doing is very much shaped by where you live, which habitats you visit and when. Just because I have not seen many butterflies on the wing during my visits to local sites does not necessarily mean they are doing badly everyway. This is why we need the efforts of scientists, operating monitoring schemes in association with ‘citizen scientists.’ The changing fortunes of our butterflies, for example, are monitored through schemes like the BTO Garden BirdWatch (which records garden butterflies on a weekly bases throughout the year) and Butterfly Conservation’s annual Big Butterfly Count (www.bigbutterflycount.org).
Last year over 30,000 people took part in the Big Butterfly Count, which runs from 14 July – 5 August, and it would be great to see even more people involved this year. The survey is simple – a 15 minute count of the butterflies seen in a sunny place – and provides information on the more familiar and widespread species. For those species of a more restricted distribution, perhaps because they have more specialised habitat requirements, or which are more difficult to identify, there are other schemes. These typically involve fewer people and use more complex methods but they provide robust and essential results, generating a long-term measure of the changing fortunes of our butterfly species.
By recording butterflies in the same way from one week to the next, or from one year to another, provides a standardised measure of change, something that allows objective conclusions to be drawn about how particular species are doing. Some of the changes revealed may be the result of natural processes, perhaps a run of poor weather or an abundance of butterfly predators or parasites, while others may be the result of habitat or climate change driven by our activities.
In order to establish the effectiveness of conservation efforts we need to be able to say with confidence whether or not a species is responding favourable and the way to do this is by systematic monitoring. This is why the work of organisations like Butterfly Conservation and the BTO is so important. Since both organisations represent a partnership with volunteer surveyors, it is easy to see the valuable roles that you and I, as individuals, can play.