Silver-studded blue butterfly (Plebejus argus) - Species Action Plan

Ref 2/S3 Species Action Plan 3
Plan Author: English Nature
Plan Co-ordinator: Heathland Topic Group
Plan Leader: Butterfly Conservation
Final Draft June 2006

Action Plan Summary

Current Status

National Status

  • The silver-studded blue has undergone a severe decline in range in the last 100 years, estimated at 80 per cent. It has become extinct in Scotland and northern England, and throughout most of central, eastern and south-eastern England. It remains widespread only on the heaths of Dorset and Hampshire, although strong populations also occur in North Wales. It occurs throughout Europe (except Scandinavia), in a wide range of habitats, including alpine grassland, meadows, forest clearings and xerophytic scrubland. However, it is declining in the west of Europe (e.g., Belgium, the Netherlands and Denmark).
  • In Great Britain, the silver-studded blue is classified as Nationally Scarce. It is protected under Schedule 5 of the Wildlife and Countryside Act 1981, with respect to sale only.

Norfolk Status

  • The species was formerly present on heaths in the north and north-west of the county and possibly in the Brecks. It has recently come to light that silver-studded blues may also have existed on the dune-slacks of the north Norfolk coast.
  • The silver-studded blue currently exists at only five colonies in the region: Horsford Woods; Horsford rifle Range; Kelling Heath; Buxton Heath; and East Ruston Common. The colony at Buxton was the result of re-introduction in 1985; the colony at Kelling was established following a formal, successful re-introduction in 2001; and the colony at East Ruston appears to be the result of a recent private re-introduction and requires further investigation. A formal attempt to re-establish a colony at Marsham in 1998 was unsuccessful.
  • Data collected over the last several years indicate that the silver-studded blue population is growing at Buxton and extending its range at Kelling. Numbers were slightly lower at Horsford rifle Range in 2005 than in previous years, probably as a result of the extensive bracken and scrub removal that had been carried out during the winter; however, it is anticipated that this will be a short-term decrease and that future counts will demonstrate a rise in numbers now that the habitat has been enhanced.

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Current factors causing loss or decline in Norfolk

  • Loss of heathland to development, forestry and agriculture has been an important factor in the past, but is currently less of a concern.
  • The fragmentation/isolation of suitable heathland habitat has also been a significant factor contributing to past declines.
  • Inappropriate heathland management, including cessation of management, continues to be a concern.

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Current Action in Norfolk

  • All five sites at which the species currently exists have been accorded national or local designations, as summarised in the table below:
  Site Designation
1 Buxton Heath Site of Special Scientific Interest
2 East Ruston Common Site of Special Scientific Interest
3 Horsford rifle Range County Wildlife Site
4 Horsford Woods Most (but not all) of the wood has been designated a County Wildlife Site
5 Kelling Heath Site of Special Scientific Interest
  • An action plan (Harris, 2000) brought together historical information regarding silver-studded blue in Norfolk and reviewed the suitability of both current and potential sites for the species. The plan also identified a number of actions for the period 2001-2003, several of which were subsequently implemented. These included the re-introduction to Kelling Heath in 2001, and monitoring of all colonies in the county by volunteers from the Norfolk branch of Butterfly Conservation.
  • The Horsford rifle Range is a privately owned site, leased to and largely managed by the Smallburgh and District Gun Club. It forms part of a Countryside Stewardship agreement and over the past five years, the Norfolk Wildlife Trust and the Norwich Urban Fringe Project have worked with the Gun Club and Butterfly Conservation to ensure that the site is managed in a way appropriate to the needs of the butterflies.
  • One of the rides within Horsford Wood (which lies adjacent to the Horsford rifle Range) also supports a colony of silver-studded blue butterflies. Forest Enterprise has carried out management work to improve the heather structure of the ride. More recently, Forest Enterprise has also agreed to fell a small area of planted conifers in order to develop a connection between this ride system and the nearby rifle range.
  • Butterfly Conservation has played an important role in promoting the conservation of silver-studded blues. In 2005, the Norfolk branch of Butterfly Conservation organised ten public training days and site visits, and also commissioned a detailed survey of existing, potential and failed sites (including ant surveys). The head office of Butterfly Conservation has published a species and habitat management fact sheet on silver-studded blues, for distribution to land managers. A species leaflet for both land managers and the public has been produced by Butterfly Conservation's Regional Officer.

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Action Plan Objectives and Targets

National

  • Maintain populations at all known sites.
  • Restore populations to former sites occupied post-1970 by 2010, using reintroductions if necessary.

Norfolk

  • Maintain, and enhance through appropriate management, populations at all five sites where the species is currently present.
  • Increase the number of colonies by two by 2010 (thereby bringing the total to seven).

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