The Atlas of Butterflies in Highland and Moray: 1980-2007 has recently been published by the Butterfly Conservation Highland branch. It provides a fascinating insight into those butterflies that have spread in the area and highlights the importance of the different species in a national context: no fewer than 11 of the resident butterflies are now listed as "priority species" and are cause for concern.

Some butterflies have significant numbers of their UK distribution in the Highlands. These include the chequered skipper that still occurs only within a few miles from Fort William and, now, nowhere else in the UK. Other butterflies with significant numbers in the Highlands are the mountain ringlet and Scotch argus. The mainstay of the Scottish population in the area include the small blue and dingy skipper.

Perhaps the most intriguing part of the atlas is the way it highlights the spread of four butterflies. The orange-tip and speckled wood have been spreading in the north of Scotland for some decades. The other two, the peacock and ringlet, have arrived much more recently, since 2000. The ringlet slowly spread northwards but with the peacock it was a different matter. On September 11 2002 it was obvious that a large influx of these striking butterflies had taken place. Weather patterns suggested the influx was from Europe into north-east Scotland around Inverness. From being a vagrant in the Highlands it has now established itself.

This last summer there were many buddleias where the commonest butterfly feeding was the peacock, closely followed by the red admiral, but only single small tortoiseshells. Is the main cause of these butterflies' arrival the series of mild winters in the north in recent years or the real, or perceived, global warming?