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Originally Posted by owenfiggis  Just been confirmed today that these are Essex skippers. The distribution map shows them to be found mostly in south and east england -I spotted these in south west scotland, dont know if this is an isolated population. Has anyone seen any in the north of England? |
Over the last half century I have been very active in recording Butterflies and especially their northward expansion. In every instance when a species moves northwards it does so first on the eastern side of the country.
At present the Essex Skipper is recorded no further north in the eastern counties than Lincolnshire. For it to suddenly turn up is SW Scotland is something which should raise a eyebrow at least. The Lepidoptera of SW Scotland is fairly well known and any small brown skipper would be noticed. It's only in recent decades that the Large Skipper has been regularly recorded there.
The Small Skipper isn't shown as recorded for SW Scotland in the latest Butterfly Conservation book containing distribution maps, but it has been expanding its range rapidly in Northumberland and could have moved over to the west coast through the Tyne/ Solway gap, the narrowest point between the west and east coasts.
The differences between the Small and Essex Skippers are slight and these points do not always show up well in photographs. Whenever there is a doubt over such an ID, a specimen should be taken alive and shown to an experienced entomologist.
How many specimens were seen at this locality? if only one or two it may well be the beginning of an influx of Small Skippers from the east. However, if these were Essex Skippers then this smacks of an introduction. Sadly many such introductions of southern species have been made in recent years, and the reasons for doing so are many. Very few are authorised scientific studies, most are by people who have bred captive specimens and have released them simply because they want to let them fly free, others do it for more nefarious reasons.
If this is a genuine Essex Skipper population in isolation it would be relatively easy to prove by DNA analysis. I consider it unlikely that this is so.
A Small Skipper record is good for SW Scotland and likely, an Essex Skipper record in the same area is IMO very unlikely, and if the specimen(s) are genuine then I suspect it has been introduced on purpose or accidentally transported into the area.
Harry.
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