Butterfly Conservation - saving butterflies, moths and our environment
Butterfly Conservation
saving butterflies, moths and our environment
White-letter Hairstreak Project 2007-2009
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White-letter Hairstreak Recording Project - How did it work?

Many people find searching for White-letter Hairstreaks difficult, but our experience in Hertfordshire and Middlesex (and through the project in many other areas) was different.

The project idea was to take the form of two phases - the finding of elm in spring when in flower and the subsequent seeds which are highly visible - and then to looking for the very active males in the treetops at the very beginning of the flight period.

A computer programme had randomly selected sixteen 10km squares from each 100 x 100km square in England, Wales and the south of Scotland, with a total of 240 areas to be sampled. Within each 10km square, just one 1km square had been randomly selected and this was the initial square to be visited.

Since these squares were completely random, there was no selection by habitat, so it was quite possible a 1km square might be in the middle of a lake or on the top of a mountain. To see the map and 10km squares selected click here................

Although we acted at co-ordinators, the idea was to engage as many volunteers from the network of Butterfly Conservation branches to do the actual ground work. First we asked that volunteers from a branch selected a 1km square from their area and that a visit was made to search for elm. Suggesting that since the flowers and seeds are often obvious in spring a visit was made then.

If recorders were positive there was no elm in the target 1km, then we asked that elm was searched for in the standard 2km square (tetrad) that contained the 1km. Again, if there was no elm in the 2km square, then we asked that elm was found somewhere in the 10km square (ideally as close as possible to the target). This may have been time consuming but we hoped that there would be some elm to be found somewhere. The ease or difficulty of finding the elm was a key component of the project. We asked for regular updates and information when suitable elm was found at 1km, 2km or 10km level and the website was regularly updated.

We requested that there should be no trespass - so that if there was no access to a 1km or 2km square because the land was private we needed to know and the remaining 10km square would be searched instead..

We then asked that once elm was found (eggs or larvae could be searched for), the volunteer revisited the elm in the flight period to look for adults reminding recorders to be wary of Purple Hairstreak and Vapourer moths. click here........

What actually happened?

Although some branches did help, especially Martin Greenland who was at the time living in Yorkshire and was an expert on finding eggs during the winter months, the general uptake was quite low.

We ended up devising a completely different strategy! We did the majority of the work, although we did use the elm reports we received to subsequently find eggs or adults.

We found the searching for eggs much more productive, and quicker as it also wasn't weather dependant and we utilised many winter visits to different parts of England and Wales. We became very skilled in finding elm, even when not in flower or seed because the flower buds are quite easy to recognise once the leaves have dropped.

We also made numerous flight period visits to many of the project targets, and were also successful in finding adults but sometimes after waiting hours for rain to stop!

In total over a period of seven years, including after the official end of the project we travelled 31,000 miles and visited every county in England and Wales and found White-letter Hairstreak in every county including Cornwall in 2013!

We didn't visit Scotland, but that has been undertaken by Jill Mills and Ken Haydock on the west side. In the summer of 2017 a single White-letter Hairstreak was recorded on the east side of Scotland by an expert recorder specifically looking for White-letter Hairstreak. In February 2018, Jill and Ken visited East Scotland and found eggs in four different 10km squares along the Tweed and a tributary the Teviot!

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