Butterflies are to be used as one of the official indicators of the health of the environment in Scotland, the Scottish Executive announced yesterday.
Rises or falls in the abundance of 21 of the 34 butterfly species that occur north of the border will join trends in other wildlife, from otters to breeding seabirds, as part of an annual health check on the state of Scotland's natural world.
Butterflies have been included because they are very sensitive to environmental change and respond quickly to a variety of phenomena, from habitat loss to global warming. They are already pointing to substantial changes that are taking place, said Martin Warren, chief executive of the charity Butterfly Conservation.
The changes are affecting two butterfly groups differently. The first group consists of more familiar species which have long been common in England but are now spreading rapidly northwards, such as the comma and the peacock – perhaps in response to climate change.
The second group, of species more localised in Scotland, such as the dingy skipper, the grayling and the large heath, is doing less well. It is believed that declining populations may be to do with habitat loss: in the case of the large heath, for example, much of the blanket bog landscape where it breeds has been drained, ploughed and planted with conifers.
The full list of 22 environmental indicators was announced by Scotland's Minister for Environment, Michael Russell. Seventeen of them are concerned with the state of the country's wildlife, and a further five are concerned with "engagement" – that is, they reflect on what the public thinks about wildlife and how far people use facilities such as natural parks. "Scotland is lucky to be blessed with unique biodiversity: inspiring landscapes, exciting wildlife, and opportunities all around us to enjoy them," Mr Russell said. "We should be deeply proud of our fantastic natural environment. However, it's clear that our natural environment faces major challenges."
Of the 22 indicators, five show improvement, three show deterioration, and five show no change, fluctuation or divergent component trends. Nine present baseline data for a new measure. In particular, four indicators reveal biodiversity responses to climate change across terrestrial, coastal and marine environments. Declines in some nesting seabirds, such as guillemots and kittiwakes, are of particular concern.
On the other hand, recovery of otters, estuarine fish, and increase of some breeding and wintering birds shows positive responses to environmental management and legislation.
The butterfly calendar
The butterfly calendar used to be reliable: we knew which species would appear when. However, climate change is altering all that, with some species now overwintering and appearing on warm winter days. As things stand, the British butterfly calendar looks something like this:
* January: red admiral
* February: peacock
* March: brimstone
* April: orange tip
* May: brown argus
* June: small white
* July: purple emperor
* August: silver-washed fritillary
* September: holly blue
* October: small copper