The Duke of Burgundy is one of the UK’s most threatened butterflies undergoing population losses of 46% between 1995-99 and 2005-09.
The butterfly is mainly restricted to the limestone and chalk of southern England, but there are two northern outposts, including the southern edge of the North York Moors which now support 10% of the UK’s remaining colonies.
The butterfly breeds on either scrubby limestone/chalk grassland or in ancient woodland clearings/rides, with larvae feeding on Cowslip Primula veris or Primrose Primula vulgaris, but only larger-leaved plants in tussocky vegetation are used.
By the turn of the millennium several colonies had become extinct in the North York Moors as the largely abandoned limestone grasslands became too scrubby and reverted to dense woodland.
In 2003 a programme of scrub and woodland management began to restore habitat on both occupied and unoccupied sites, the aim of which was to prevent further extinctions and encourage recolonisation of former sites. As a result of established working relations with landowners and the availability of funding, much more work was undertaken in the Helmsley habitat network compared to that in Pickering.
- Small-scale scrub management, removing small groups of shrubs and trees.
- Large-scale scrub management to create glades in woodland or restore more extensive areas of grassland, retaining scrub margins but pushing them back to create bare ground for Primula spp.
- Mowing rank grassland, Bracken control and Cowslip planting on a few sites.
For more detailed information about this project and others across the UK please read the full report: Landscape-scale Conservation For Butterflies And Moths: Lessons From The UK.
- The Helmsley metapopulation has now been stabilised, with a single further extinction balanced by two re/colonisations, in contrast to the Pickering metapopulation which has declined to a single colony.
- Between 1999 and 2011 the population in the Helmsley network increased by 395% in comparison to a decline of 78% in the Pickering network.
The project demonstrates the cost benefits of early intervention. The cost of management in the first phase was only £21k, in comparison to £110k for a follow-up second phase. The second phase focuses effort in both habitat networks, but with significant proportion directed at the Pickering network, where sites have become progressively more unsuitable over time and where strategic re/introductions will be needed to fully restore the metapopulation.