Recently I was lucky enough to find a second-hand copy of "The Butterflies of Scotland" by George Thomson. This was writen in 1980 and I was keen to see the distribution maps and compare them with those in the 1970 "Provisional Atlas of the Insects of the British Isles" and with the current distribution maps produced by Butterfly Conservation. However, I was delighted to discover that the author has also included the history of records for each species going back to the early 1800s.
I have been spending hours reading this book and learning about how the distribution of many species of butterflies has changed over the years. Some of what I have read confirms what people have told me but there were a few surprised in there too!
I will start with some now common butterflies. The Orange Tip, Anthocharis cardamines, is said to have been widespread throughout southern and east Scotland in the early 1800s and it remained so until the 1880s, but after that its range contracted to south west Scotland. In about 1950 it was considered to be advancing back towards the Lothians. The map in Butterflies of Scotland shows it occurring in South-west Scotland and the Highlands, with one or two records in between. My boss, who was a countryside ranger in the 1970s says he remembered them only being along the River Esk in the west of East Lothian. Since then they have spread and they are now commonly seen in the spring across much of East Lothian and Scotland.
The Peacock, Aglais io, was recorded in south west Scotland in the 1700s and it continued to be recorded there through the 1800s with sporadic records across Scotland. However, by the start of the 1900s it was becoming rarer. It is thought that small colonies persisted on the west coast of Scotland, but that other records from around Scotland were migrants. Records started to pick up again in the 1950s and since then it has continued to spread across Scotland. It wasn't until the 1980s that it was found in East Lothian.