Butterfly Survey Training Report

Saturday, 29^th March 2025, dawned bright and clear with a bit of warmth in the air, perfect for our butterfly survey training at Long Mead Local Wildlife Site.

  

Peter set up a practice 'transect': 2 sections, each about 150m long on the edge of the main track and stream. It was too early in the season to rely on real butterflies, so he used surrogates - clothes pegs in this case. These were set out to imitate what butterflies tend to do - though none of our clothes pegs were flying around! Some were high, some were low, some were close, others further away; there were gaps with no butterflies (pegs) and other areas where there were clusters, etc.

 

There was a fabulous turn out for this training with over 20 people turning up, split evenly between Nature Recovery Network and Upper Thames Butterfly volunteers. The level of knowledge and experience within the group was quite mixed, with some people who were very much beginners and others much more confident in their ID of the common butterfly species.

 

 

Peter introduced two of his favourite books. The Butterflies of Britain & Ireland by Jeremy Thomas and Richard Lewington which is an absolute font of information and has beautifully observed, large clear illustrations and the Pocket Guide, which is his 'go to' field guide.

 

Jeremy Thomas was one of the early movers in the butterfly conservation movement. Richard Lewington is one of the world's leading insect illustrators, as well as being an Oxfordshire resident. His pictures are truly magical.

 

 

Peter recommended the free Butterfly Conservation app iRecord Butterfly, which uses your phone's GPS to establish where it is and its calendar/clock to establish when it is looking. It provides you with illustrations of all the butterflies you are likely to see in the moment, now - in order of the most to the least likely. It also provides much background information about each species. However, the most important part, from a conservation point of view, is that it allows you to record what you have seen and send it directly to the National Database (National Biodiversity Network) where the record is vetted and added to the archives (this is really valuable). You can even add a photograph of your butterfly if you are unsure of its identity.

 

Peter then introduced his friendly 'twizzle stick' (imitation butterfly attached), to demonstrate that no one is likely to be able to identify every butterfly we saw. He demonstrated the need for reliable and comparable records so that we could compare sites and seasons, to establish how our butterfly species are fairing. He also went through the detail of using 'Pollard Walks': a 5m imaginary cube that moves along the transect in front of you - and you can only count those species that enter the cube but must discard those that enter from the back (you may have already counted them).

 

 

He explained the difference between 'transects' (mostly in nature reserves or areas managed for nature conservations) and WCBS (Wider Countryside Butterfly Survey - in the wider countryside - farmland, forestry, etc). In each case, you walk a fixed route between 10:46 and 15:45, when the temperature is 13°C or above, the sun 60% or more and the wind in no more than Beaufort scale force 4. The main differences are that transects are walked every week from 1^st April to the end of September every year; whilst the WBCS squares only have to be walked once in July and again in August (though extra months can be usefully done). Most transects take between 45 minutes to an hour to complete each week. The WCBS squares tend to be a bit longer, often taking up to 2 hours each month.

 

When the temperature rises above 17°C, you can walk your transect/WCBS even if there is no sunshine but should never start when it is raining. If it starts to rain when you are more than half-way through your survey - just continue. If before half-way, it is best to abandon that attempt and try another day.

 

We looked at the recording sheets and practiced filling in the general data before going outside for our practice. Once outside, Peter demonstrated what a 5m cube might look like and the sort of pace expected for surveys (quite slow!). We also discussed the fact that you should not stop to search for butterflies nor wait at a favourite spot to see particular butterflies. There were two sections in our practice transect, so we set off in pairs - one observing and the other recording in the first part, then swapping for the second part. 

 

At the end of the route we discussed how easy it was to judge if the butterfly was in you cube and how we all miss some of the butterflies even when they are static pegs. Though, of course, real butterflies move, so are easier to pick up. 

 

Our many thanks to Peter for carrying out the training, the buttefly survey group will be meeting in the coming weeks to discuss Nature Recovery Networks transects and where to survey.