Butterfly Conservation - Upper Thames Branch

Silver-washed Fritillary Report 2006-7

Mick Campbell

Many thanks to everyone who sent in sightings of Silver-washed Fritillary, in particular Chris Brown who monitored Crowsley Park Wood on a daily basis throughout the season, capturing the timing of different events, such as pairing and roosting habits of this beautiful butterfly.

From the left: Silver-washed Fritillary male on bramble showing the distinctive black streaks of scent-scales near the middle of the forewing;

female on buddleia; and the valezina form of the female (photos © Peter Hall, David Redhead & Tony Croft respectively)

The Silver-washed Fritillary is a strong, fast flying woodland species, preferring mixed woodland with an open canopy, sunny glades and rides, with bramble as the favoured nectar source. They lay their eggs on oaks and rough-barked conifers where their foodplant of violet is present nearby. Interestingly, a report was also received from Jan Haseler in 2007 of a female appearing to oviposit on alder.

Silver-washed Fritillary has been expanding its range in recent years and in the hot summer of 2006 it was particularly successful, with ‘wanderers’ turning up in 12 gardens, compared with 3 sightings in gardens during the 2007 season.

	First sighting	Last sighting	Number seen
2006	22-Jun-06	24-Aug-06	389
2007	17-Jun-07	07-Sept-07	306

As this species has a very long flight period, the peak emergence is difficult to pinpoint, but the maximum numbers are counted from about 11^th July through to 10^th August, with the first females being noted 2-3 weeks after the first male is sighted. Pairing was observed on 11^th and 17th July in 2006. In both 2006 and 2007 the last Silver-washed Fritillaries reported were males.

Unlike the colonies of Silver-washed Fritillary further south where oak is the preferred tree on which to oviposit, in this area they appear to prefer conifers. On two occasions a female has been observed egg-laying on rough-barked conifers such as the one shown below.

Conifer plantations were planted in this area about 50 years ago for paper and timber production - are they now at a height which suits the Silver-washed Fritillary? Perhaps these conifers have enabled this species to expand their range further north, although the warmer temperatures due to climate change could also be a contributory factor.

Another consideration is that we’re experiencing much higher winds in this country which has opened the tree canopy in some woods, providing the dappled shade conditions favoured by Silver-washed Fritillary.

From the left: Rough-barked conifer in Homefield Wood and Violet plant in Crowsley Park Wood

(photos © Wendy Campbell & Chris Brown respectively)

Woodland management can provide these conditions and a good example can be seen in Homefield Wood where the Forestry Commission has widened the rides and removed quite a few trees. This has benefited the Silver-washed Fritillary in recent years and their numbers in this wood have increased from the occasional sightings in 1988 and 2003 to regular sightings in 2006 (12 sightings) and 2007 (22 sightings).

Finally, the Silver-washed Fritillary is a popular butterfly for breeding and it is known that releases occur into local woodlands, making interpretation of this species’ response to the effects of woodland management more complex.

It’s very difficult to get an accurate count of Silver-washed Fritillary as they are such mobile butterflies, however significant/good-sized colonies (20+ sightings) have been found in:

Wendover Woods (owned & managed by the Forestry Commission for recreation, conservation and timber production – Silver-washed Fritillary was a possible release here a few years ago which may have swelled the numbers, but the colony seems to be thriving at present).
Crowsley Park Wood (Forestry Commission – management plan is on-going and available on the internet)
Noke Wood (private – contact made with the owner)
Warburg Reserve (BBOWT)
Bowdown Wood (BBOWT)

Two other sites deserve special mention as Silver-washed Fritillary seems to have recently established colonies there:

Homefield Wood (Forestry Commission & BBOWT - conditions improving, as mentioned above.)
Moor Copse (BBOWT – first Silver-washed Fritillary seen in 2005; numbers increasing since.)

The outlook for Silver-washed Fritillary is positive provided woodland management is sustained and the temperatures stay warm. In 2008, assuming the weather is kind to us, the following are suggestions as to how you can help study this species:

If possible, identify whether individuals seen are male or female (this helps build up a picture of their emergence pattern and behaviour);
Confirm existence of Silver-washed Fritillary in known woodland locations (see list below);
Survey woods where Silver-washed Fritillary hasn’t been recorded previously;
Check for the presence of the foodplant (violet), especially near the base of conifers, in woods where Silver-washed Fritillary is found;
Watch for mating pairs, often quite low down on trees or shrubs (confirms site is suitable for a colony to exist);
Watch for females laying eggs (females will be seen fluttering slowly along the ground or around the lower part of a tree trunk, then landing to oviposit);
Watch for roosting behaviour (usually high up in trees).

List of locations where Silver-washed Fritillary was recorded during 2006 and 2007

Grid Ref.	Location
SU703649	Beech Hill, Berks
SP618111	Bernwood
SP460140	Bladon Heath
SU5065	Bowdown Woods
	Bradenham Hillsides
	Calvert Jubilee reserve (permit only)
SP847067	Coombe Hill, Ellesborough
SU735795	Crowsley Park Wood
SP902092	Dancersend
SP699164	Disused RW, Westcott
	Farley Hill
SU515716	Fence Wood, Hermitage, Berks
SP7121	Finemere Wood
	Fingest - private wood
SU39	Gainfield (west)
	Garden in Fingest
	Garden in Littlemore, Oxon
	Garden in Marcham
	Garden in Marlow, Bucks
	Garden in Southend (nr Stonor)
	Garden nr Tubney, Oxon
	Garden nr. Little Chalfont
	Garden nr. Loosley Row
	Garden nr. Pangbourne
	Garden nr. Whitchurch-on-Thames
	Garden nr. Wychwood Forest
	Grangelands
	Grendon area
	Hatchet Wood, Bucks
	Holton Wood
SU813868	Homefield Wood
SP957155	Incombe Hole
SP6919	Kingswood (on public footpath)
SP665311	Lenborough Wood, north Bucks (private - strictly by permit only.)
SU788932	Leygrove's Wood
SP8345	Little Linford Wood (BBOWT - 5km s. of Salcey Forest)
SP6215	Little Wood (permit only)
SP62951035	M40 Compensation Area
SU854808	Maidenhead Thicket, Berks
SU634740	Moor Copse
SP558115	Noke Wood (footpath on edge - wood is private)
SP557116	Noke Wood (interior - permit required)
SU765938	Penley Wood
SP544125	Prattle Wood (private)
SU655761	Purley on Thames
SP653310	Round wood
	Rushbeds Wood & meadow.
SP614108	Shabbington Wood
	Sole Common
	Stanton Gt. Wood
SP5527	Stoke Wood
SU772677	The Coombes, Arborfield (but sighting possibly in Barkham.)
SP6531	Tingewick Wood
SU4398	Tubney House, Tubney
SU7287	Warburg Reserve
SP605090	Waterperry Wood
SP883076	Wendover Wood (Picket Piece)
SP887100	Wendover Woods (Aston Hill)
SP8808	Wendover Woods (Halton Wood)
	Westwood Country Hotel, Oxon (permission reqd)
SP6014	Whitecross Green Wood
SP822038	Whiteleaf, by the notice board for the tumulus.
SP334185	Wychwood Forest (main road)