Large Blue - Nick Edge

Our most threatened butterflies and moths are often dependent for their survival on habitats, such as deciduous woodland or chalk downland, which are increasingly rare in the UK’s countryside. In such places butterflies and moths can find all the resources they need, including nectar for the adults and the right plants for their caterpillars to eat.

However, if those sites are small they can only ever support small numbers of butterflies and moths and are very vulnerable to extinction. An accidental fire on a small heathland for example, could easily destroy all the habitat for the Silver-studded Blue butterfly, whereas on a larger site, some of the habitat might remain unburnt allowing some of the butterflies to survive until the vegetation recovers.

Our countryside is increasingly fragmented, with the best wildlife sites often occurring in a ‘sea’ of unsuitable habitat and so if a site is isolated as well small, the chances of it being recolonised by the butterfly or moth following an extinction are pretty small.

With our improved understanding of butterfly and moth populations, we now know it is best to concentrate our conservation efforts on multiple sites which are reasonably close together rather than on single isolated sites. In other words a landscape-scale approach.

First we carefully target habitat improvements (e.g. coppicing woodland; clearing scrub from chalk downland) on sites where a threatened species is still present (occupied sites) in order to build up population numbers. Next we target habitat improvements on nearby sites where the species used to occur (former sites) or could occur (potential sites). Thirdly we try and improve the connections between sites (e.g. by widening a woodland ride, planting a flower-rich field margin) to encourage some butterflies and moths to leave the occupied sites and recolonise the former and potential sites. A successful landscape conservation programme means there will be more sites occupied by the butterfly or moth than at the start.

The report, Landscape-scale conservation for butterflies and moths: lessons from the UK, provides concrete evidence that action aimed at conserving butterflies and moths at a landscape-scale have enabled threatened species to flourish after decades of decline.