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2011 Update on Norfolk Silver-washed Fritillaries

Whilst not especialy uncommon nationally, Silver Washed Fritillary is a rarity in Norfolk. It was a County breeding species several decades ago but now it is only encountered rarely as an incoming migrant.

During 2010 there was an unusually large number of sightings leading to the hope that it might become re-established as a Norfolk breeding butterfly. The Silver Washed Fritillary was reported with increased frequency in our neighbouring counties of Suffolk and Cambridgeshire and seemingly locally bred individuals were found this year at several new sites.

Having been lucky to see the species in Norfolk during 2010, I was interested to search for it again this year. Fortunately, I found it at two locations in North Norfolk, Foxley Wood where it was present in 2010 and another site where seemingly it was not recorded last year. It is unclear whether these 2011 butterflies were migrants but both male and female individuals were present from late June and through July.

As well as getting a few photographs of both sexes, the real highlight was to observe their courtship flight. The Silver Washed Fritillary has a complex mating ritual that starts with a characteristic courtship flight in which the female flies in a straight line followed by the male which continuously circles under and in front of her before flying back over the top to the back of the female. I watched this for several minutes on a sunny July morning before the pair disappeared from view. The scales present on the characteristic, black wing bars of the male are used later in the mating ritual.

Whilst the 2011 butterflies are not definatively Norfolk bred, the presence of both sexes over a prolonged period as well as the observation of their courtship flight bode well for the species in the 2012 season.

Another observation is that the species can be quite elusive and I found it essential to use a really good sunny "butterfly day" to have a fighting chance of seeing them. Seemingly they are happy to live in the woodland canopy at other times and hence may be present in areas where they are not readily encountered.
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