BUTTERFLY CONSERVATION UPPER THAMES BRANCH

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Dingy Skipper Report 2008

Dave Wilton

Levana database records for the period 1991 to 2008 show the Dingy Skipper to have been present in a combined total of 150 different tetrads in the Upper Thames region. The data from 2001 onwards is broken down as follows:

2001	13 tetrads	(28 records, >100 individuals)	21 May to 20 Jun
2002	29 tetrads	(82 records, >180 individuals)	21 Apr to 4 Jul
2003	42 tetrads	(113 records, >300 individuals)	22 Apr to 20 Jun & 10 Jul to 21 Aug
2004	52 tetrads	(172 records, >660 individuals)	2 May to 22 Jun
2005	37 tetrads	(126 records, >660 individuals)	1 May to 27 Jun; 31 Aug
2006	31 tetrads	(78 records, >350 individuals)	22 Apr to 21 Jun
2007	38 tetrads	(101 records, >560 individuals)	19 Apr to 10 Jun; 24 Jul to 10 Aug
2008	35 tetrads	(82 records, >460 individuals)	3 May to 5 Jul

With such a wide variation in annual record totals it is not really possible to gain a meaningful comparison between individual years.

While it is tempting to suggest that the overall reduction from 150 tetrads (1991-2008) to 100 tetrads (2001-2008) shows a significant decline, it is possible that a good number of the "missing" sites simply have not yet been visited this century. The database does not show "negative" sightings so more work will have to be channelled specifically towards searching for colonies not recorded since the year 2000.

My own impression is that the species did reasonably well in our three counties during 2008. The first sighting nationally appears to have been on 14th April (in Glamorgan), which was a week later than in 2007. The first sighting in our region was provided by Tony Speight at Sands Bank in High Wycombe, Bucks on 3rd May and reflects the delayed start suffered by many species in 2008 due to the poor spring weather. Also, there is normally a difference of about a week between the emergence at sites in the Chilterns and Berkshire Downs when compared to those on the lower-lying clay, but this wasn't the case in 2008.

The first record at my local colony on the disused airfield at Westcott, Bucks, which had been checked regularly since 26th April 2008, was on 5th May. That colony built up quite rapidly to a peak of 20+ individuals recorded on 11th May. Two adults were still active on 17th June and that turned out to be the final sighting there. These records come from the publicly accessible part of the site that lies along a public footpath through the disused railway cutting on its western edge. The main part of the old airfield is now a secure business park and to date access to it has not been possible, but ecological surveys in connection with planning applications have confirmed that the butterfly exists there as well, so this could be quite a significant meta-population.

John Lerpinière kindly showed me the colony at Paices Wood near Aldermaston, Berks (a former gravel extraction site) which he discovered in 2006. During the 2008 season I also managed to visit a handful of chalk downland sites in the Bucks Chilterns, at Aston Clinton Ragpits, Buttler's Hangings, Grangelands and Ivinghoe, and found the species thriving at each of them. However, most of my time was spent at lowland colonies in mid-Bucks. Besides the colony at Westcott I also visited Dingy Skipper sites at Calvert BBOWT Reserve, Calvert Green and Greatmoor (all former clay extraction sites surrounding the massive Calvert land-fill) as well as railway cuttings at Rushbeds (active, with permission from Network Rail) and near Salden Wood (currently disused), all of which produced the butterfly. The Salden Wood site, which is also home to two other BAP butterflies (the Grizzled Skipper and Wood White), will be affected by plans to re-open the railway line between Calvert and Bletchley and the branch will be seeking to have the welfare of each of these species taken into account by the developers.

The Dingy Skipper has traditionally been a butterfly of woodland clearings as well as the chalk downland and brown-field sites with which we normally associate it. Woodland is the one area of habitat from which we may be in danger of losing the species. My one surviving local woodland colony (Finemere Wood in Bucks, a very well recorded BBOWT reserve) produced a single sighting of one butterfly on 6th June, quite late into the flight period. The same meagre total was achieved over the previous three years with singletons found on 6th June 2005, 3rd June 2006 and 2nd June 2007, which does at least go to show that the butterfly has the ability to hang on in incredibly low numbers. A major operation to extract conifers from Finemere will begin later in 2009 and could well create better habitat for the species there, if it isn't already too late. It may still be worth checking other woodland sites that have produced no records in recent times.

On 9th May 2008 I visited the site of a historic Dingy Skipper colony in a wild-flower meadow near Stonesfield, Oxon but found no sign of the species there. I was unable to get back to the site later in the flight season but it will be worth checking again because there is plenty of bird's-foot trefoil in the meadow. Rather pleasingly, during the 2008 season Dingy Skipper sightings were made at two sites for which we have no previous records, one near to the Ridgeway to the southeast of Ashbury in West Berkshire and the other south of Hook Norton in Oxfordshire.

In 2007 there was a partial second brood of Dingy Skipper at a few of the Upper Thames downland sites. While there were reports of a second brood from Hampshire in August 2008, no such sightings have been reported to me from our area.

On 20th May I watched while a female Dingy Skipper laid an egg on a bird's-foot trefoil leaflet at the Westcott disused railway cutting and the egg was then photographed. On 7th June I managed to locate the newly emerged caterpillar, which was feeding on the same leaflet which it had loosely rolled up into a tent (this was again photographed, but with a different camera which did not have such good close-up capabilities!). Unfortunately I was unable to relocate the caterpillar on 17th June or on subsequent visits.

~~oOo~~

All photographs © Dave Wilton.