A Surprising Discovery

I often go into Beckley Woods. I try to go once a week around lunchtime once the weather starts to warm up. A lot of habitat improvement has been carried out by the Forestry Commission and contractors as part of Butterfly Conservation’s Rother Woods Project, something I was very involved with from its inception.

The work is really paying off and the current ranger is very keen to help ensure the habitat is looked after, which is very welcome. The difference the work has made is very noticeable – rides which were previously crowded in have been opened up and the butterflies have responded well. Adder

On Wednesday, I decided to have a short walk and a sandwich and took my camera in the hope of seeing Brimstone or perhaps another Adder, as I had the previous week.

So, this is how I came to be quietly padding through the bracken on the south side of a ride, on the lookout for more of this beautiful snake.

Instead,  I noticed a butterfly basking on the bracken, wings flattened down against the warm surface making the best of the lunchtime sunshine. I immediately thought it looked big for a Tortoiseshell and then as I crept closer I reached for my camera as my suspicions peaked. I was sure it was a Large Tortoiseshell*(see below!) – a butterfly I had never seen in my life and extinct in the UK for a long time – but because of its status I thought I had better get a picture before it flies off, so I can confirm it.

Large TortoiseshellIn the end, I got quite a few shots, as it just lay there even as I adjusted settings on my camera. Indeed it only flew off when I touched it to make sure it was actually alive! Once home, I checked my Richard Lewington book (naturally) and confirmed I wasn’t going mad (at least not over this anyway) and then let a few people know.  This specimen is almost certainly an individual that migrated across the channel last summer and has hibernated in the wood. A number of Clouded Yellows were seen here last summer (also migrants) and this woodland is very close to the sea via the Tillingham Valley.

UPDATE: This discovery turns out to be even more surprising than first thought! The butterfly is in fact a Scarce Tortoiseshell, and the first record of one since 1953 and the first ever record of an overwintered specimen in the UK. The following is reproduced from the Sussex Butterflies website:

Scarce Tortoiseshell Update: While Michael Blencowe was preparing his talk for the BC Sussex AGM, he was scanning through some older pages on the Branch website. Having swotted up on the differences between Large and Scarce Tortoiseshell, he became deeply suspicious that the butterfly labelled as a Large Tortoiseshell, seen by Stuart Cooper in Beckley Woods (East Sussex), was in fact a Scarce Tortoiseshell! He rang me to ask for a second opinion and as I brought the old image up I nearly fell off my perch! The date …. 12th March 2014! This implies that the butterfly had overwintered in East Sussex and must have arrived in the UK during the summer of 2013. Although the species was undergoing a further phase in its rapid range expansion at this time, spreading northwards and westwards in southern Finland, and westwards through southern Sweden (Manil & Cuvelier, 2014; Fox et al, 2015), this new Sussex record remains well ahead of (observed) incursions into Norway, Denmark, Germany, Netherlands and Belgium, during July 2014. Unless the history of an imported woodpile on Shetland, which contained a sleepy Scarce Tortoiseshell (November 2013), can be accurately determined, this places the Beckley Woods specimen ahead of the post-1953 pack (the sole, previous British record being a 1953, Kent specimen). A great bit of detective work by Mr Blencowe. The cat has been put firmly amongst the pigeons! (Neil Hulme)

Patrick Barkham wrote this Scarce Tortoiseshell this year, but at the time we were all unaware that it had occurred a full year earlier, in the humble Beckley Woods.

Back in the 19th Century, the Large Tortoiseshell butterfly was plentiful in Sussex and Kent – even “of frequent occurrence in Burnt Ash Lane, Lewisham in 1856” and generally distributed across Surrey, Suffolk, Lincolnshire and more, according to my 1889 copy of E. Newman’s “Natural History of British Butterflies and Moths”.

The Scarce Tortoiseshell is a European species which has never been resident in the UK. Perhaps this is the early stages of a colonisation.

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