BUTTERFLY CONSERVATION UPPER THAMES BRANCH

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Silver-washed Fritillary Report 2010

Mick Campbell

Photo © Derek Haynes

Following an excellent year in 2009, the Silver-washed Fritillary had another good year in UTB in 2010, both in terms of the number of sightings and the size of the established colonies.

The first sighting in UTB was on 21st June in Kingswood, Bucks and the last sighting was on 2nd September in Crowsley Park Wood, Berks. Total sightings were 524 and peak numbers were reached during the second week of July following some warm, dry and mostly sunny weather.

Poor weather, including thunderstorms and exceptionally strong winds around the 14th to 17th July caused a dip in sightings. High pressure then returned the weather to warm and dry conditions and this created a second, smaller peak in sightings during early August.


   
  2006 2007 2008 2009 2010
Total Sightings 389 306 197 557 524
Garden Sightings 14 3 3 15 9
f. Valezina 2 1 2 6 11

 

As you can see from the table above, there has been a significant increase in the number of the Valezina form of the Silver-washed Fritillary, which used to be restricted to the warmer Southern counties.

In 2010 it was recorded in 6 woods in Bucks, 1 wood in Berks and, most surprisingly, a garden in Bucks. It will be interesting to see if Valezina numbers continue to rise in coming years.

 

f. Valezina
Photo © Derek Haynes

Colony sizes continue to expand in a significant number of woods including (numbers are the maximum sightings recorded at any one visit to the site):

  • Bernwood, Bucks - numbers recorded on transect were at an all-time high. 2 (2006), 18 (2010 - Shabbington Wood transect)
  • Waterperry Wood, Bucks - 3 (2006), 20 (2010)
  • Stanton Great Wood, Bucks - this private wood is currently only surveyed from the public footpath running around the edge. A survey of the interior might reveal a larger colony than the 8 counted from the perimeter. 2 (2007), 8 (2010)
  • Homefield Wood, Bucks - this colony continues to do very well since the conifers were thinned out and the rides widened. Courting Silver-washed Fritillaries (the male flying in loops around the female) can often be seen along the main ride on a sunny day. Peak numbers in this wood were 36 in 2009.
  • Moor Copse, Berks - the colony at this site is expanding rapidly: 3 (2006), 28 (2010)
  • Black Park, Strawberry Wood, Berks - 0 (2006), 10 (2010)
  • Crowsley Wood, Berks - 12 (2006), 31 (2010)
  • Penley Wood, Bucks - This colony has increased rapidly and half a dozen individuals could be seen on each sunny bramble patch along the main ride in 2010: 1 (2006), 3 (2007), 31 (2010)
  • Romer Wood, Bucks (public footpath only) - 0 (2006), 3 (2008), 26 (2010)
  • Rushbeds Wood, Bucks - 1 (2006), 2 (2008), 8 (2010)
  • Hartmoor Wood, Ibstone, Bucks - (new site) 12 (2010)

    		•

    Homefield Wood main ride (Summer 2010) - click images to enlarge
    Photos © Malcolm Brownsword

    Contact has been established with the landowners of Penley Wood this year and they have expressed their keen interest in butterflies and conservation.

    The colony in Wendover Woods is still thriving, although numbers were down on the previous 2 years due in part to poor weather on the survey day: 25 (2009), 15 (2010).

    Finemere Wood is being opened up this winter by the removal of conifers which will hopefully prove beneficial to the Silver-washed Fritillary colony.

    Chinkwell Wood has always been very poor for this species with a maximum of 4 being seen in any year over the last decade. This wood has been opened up significantly in 2010 with the removal of many conifers. It will be interesting to monitor this wood over the next few years to see if numbers increase. The foodplant is present in the wood.

    Whitecross Green Wood, Oxon, will also be interesting to watch as the trees are being thinned out during this winter which will allow more light into the wood. A mating pair of Silver-washed Fritillary was recorded in the wood this year.


    Egg laid on moss in a garden
    in Shipton-under-Wychwood, Oxon
    Photo © Hamish Fenton


    There have been no reports of larvae found in the wild, however there were four sightings this year of Silver-washed Fritillaries ovipositing:

  • 11th July, Shotover, Oxon : Egg laid on moss on a dead elder. Violets found at the base of the elder. The nearest colony is probably Waterperry Wood or Stanton Gt. Wood, both approximately 5 kilometres to the north-east.
  • 15th July, Rushbeds Wood, Bucks : Egg laid on moss on the trunk of a sallow.
  • 2nd August, Wendover Wood, Bucks : Egg laid on an oak log.
  • 20th August, garden in Shipton-under-Wychwood, Oxon : Egg laid on moss. No woods in close proximity but there are violets in the garden. The nearest colony is probably in Wychwood Forest, approximately 5 kilometres to the east, where 10 adults were recorded in 2008.




    • Thanks very much to everyone who sent in sightings of Silver-washed Fritillary this year. There are too many people to list here. The additional photos and notes which accompanied your reports have helped build up an interesting picture of the behaviour of this graceful butterfly.

    Mick Campbell
    December 2010

    ~~oOo~~

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