A quickfire season for Northern Brown Argus up here in South east Scotland during 2018 as most adults emerged in a short window from the first week in June after a slight delay on the coast due to easterlies. This year I saw the species in numbers throughout the entire length of the Berwickshire coast as well as sizeable colonies inland around the Lammermuir Hills and Lauderdale. The surprise colony of 2018 for me was the discovery of Northern Brown Argus on the Eildon Hills at Melrose. The Eildons are mostly acidic and hold no Common Rockrose, though one of its hills, Little Hill, is calcareous and has held Common Rockrose for many years. Because the hills have been so popular with naturalists for many, many years, much is known about the ecology, Flora and Fauna. Northern Brown Argus have just never been recorded in all of history,until this summer. A visit to the site by Bryologist David Long, who was keeping a weather eye open for the species, recorded several adults on the west side of the outcrop in late June. I visited the site for confirmation and found the Butterfly in numbers on a hot day on the 3rd of July. The conundrum was how had they been missed all this time considering the number of Butterflies present. The Little Hill is completely isolated in the landscape from any nearby colonies of Northern Brown Argus, or indeed Common Rockrose. Had the sight recently been colonised at distance? Has this site always been colonised and just been missed? I don't think they could have been here for so long and been missed, and I don't think from what I saw that this is a newly colonised site, as the site is centuries old...so I would say at best, that this site, because of its isolation in the landscape, has been recolonised by nomadic Butterflies from as far away as 10 miles. I have seen this species in the landscape on several occasions in a fresh state up to 5 miles from any known Common Rockrose through the years, and see it very regularly travelling through arable landscapes at a mile from coastal colonies. My theory is that a number of triggers can force this shift, mostly climatic, or habitat pressures. Does the species have a secondary food source to sustain itself away from its core historical sites that contain Common Rockrose? Geranium sp perhaps? How do Northern Brown Argus navigate the landscape to re find these isolated sites in order to recolonise.? Is there an inherited map of the landscape, a road map to old sites handed down to the offspring generation after generation. Sounds a bit far fetched I know, yet something is going on, and I can't quite figure it out.
Through 12 years of observing Butterflies at a local level I have seen Butterflies turn up in the oddest places, far from known colonies, yet somehow....when later studying maps and reading historical accounts, those wandering species seem to be revisiting habitats that no longer exist along well worn corridors of landscape. There is a pattern...but as I say...I just can't quite see it yet. The discovery of Northern Brown Argus on Little Hill is something we can get our teeth into,and studying how long they can sustain this colony on Little Hill will be very interesting indeed.
All the photos from the coastal colonies around Eyemouth and Burnmouth as some of you will recognise.
There's only two days now until the obese male pensioner in the red suit commits reverse burglary so to one and all; Have a Happy Christmas! 
