Saturday, 29 July 2006

Charity champions declining butterflies

This week has been designated ‘Save our Butterflies Week’ by Butterfly Conservation, a charity dedicated to the conservation of our various Lepidoptera (as butterflies and moths are known collectively). The week follows a new report into the changing fortunes of our butterflies, also published by Butterfly Conservation. The report, “The state of butterflies in Britain and Ireland” makes worrying reading, such has been the magnitude of decline for many formerly widespread species.  Norfolk itself has lost a quarter of its resident butterflies. Included among these are the large copper (which became extinct in 1864), small blue (1890s), chalk-hill blue (1971) and marsh fritillary (1970s). That we have lost so many species is a reflection of the changing land management and the loss of important habitats. The large copper, for example, was dependent upon areas of open fen, with high densities of the larval foodplant water dock, and as these disappeared so did the butterfly. Other species, like the high brown fritillary and the purple emperor have been lost as woodland habitats succumbed to modern management techniques.

For other species there is better news contained within the Butterfly Conservation report. The efforts of researchers, conservationists and volunteer lepidopterists have helped to secure the future of a number of species. The Norfolk Branch of Butterfly Conservation has been working hard to assess the habitat requirements of the silver-studded blue, a rare species, with a cluster of small colonies centred on the mid-Norfolk heaths. This delightful butterfly flies from June through into August and efforts have been made to see the number of colonies increase. The work, funded through the Heritage Lottery Fund has enabled the Norfolk Branch to hold training days, enabling volunteers to identify and monitor populations of this butterfly. The grant also funded a detailed study of all current and potential sites for the species within the county, with data collected on the condition of the heathland vegetation and on the densities of local ant populations (like a number of other blue butterflies, the silver-studded blue has a symbiotic relationship with one or more species of ant).

The result of all this work is a management plan for the species within Norfolk. The plan has established the size of the current silver-studded blue population and where it occurs. It has also highlighted sites where it is hoped that the butterfly can be established by moving a small number of individuals from existing sites with healthy populations. With luck, and quite a bit of effort, the future of the silver-studded blue should be secure. Now all we need to do is work on some of the other species that have declined over the years.

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