Current status
The silver-studded blue occurs on lowland heathland, calcareous grassland and at a single peatland site in Wales. In all habitats, the species requires the presence of ant species of the genus Lasius, open ground for breeding, and either bare soil or short vegetation. The preferred conditions produce warm microclimates at ground level for the larvae, a factor that is especially important towards the north of the species` range. Early successional stages are preferred, particularly where succession is held in check by grazing. Most heathland colonies exist on sites that have been either recently disturbed, such as sand pits, quarries and firebreaks, or burnt. Conditions usually become suitable after 2-5 years of re-growth. In the absence of traditional management (such as the cutting of heather and invasive scrub, grazing of domestic animals, or burning to encourage young growth for livestock), suitable conditions on heathlands are short-lived, perhaps lasting 5-10 years. In most situations, the silver-studded blue appears to exist in metapopulations, with patches of suitable habitat linked by the occasional dispersal of adults.
The silver-studded blue has undergone a severe decline in range this century, estimated at 80%. 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, occurring in a wide range of habitat, including alpine grassland, meadows, forest clearings and xerophytic scrubland, but it is declining in the west of Europe (eg 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.
Current factors causing loss or decline
Loss of heathland to development and agriculture
Fragmentation and isolation of habitat.
Inappropriate heathland and grassland management .
Increased quarrying activities, particularly on the Isle of Portland, Dorset.
Current action
A species action plan, grant-aided by CCW, NE, SNH and WWF, was published by Butterfly Conservation in 1996.
The silver-studded blue is well represented on nature reserves, SSSIs and other protected areas. Several populations are present on candidate SACs.
In 1995 NE published a booklet on the conservation of the silver-studded blue in lowland heathlands.
A number of introductions and reintroductions of the silver-studded blue have been attempted by conservationists including well-documented introductions in North Wales and Suffolk.
Three silver-studded blue populations are covered by transects operated under the Butterfly Monitoring Scheme and many more are covered by independent transects undertaken by site managers or volunteers.
Action plan objectives and targets
Maintain populations at all known sites.
Restore populations to former sites occupied post-1970 by 2010, using reintroductions if necessary.
Proposed actions with lead agencies
Policy and legislation
Where appropriate, include the requirements of the silver-studded blue when preparing or revising prescriptions for agri-environment schemes. (ACTION: CCW, NE, FC, MAFF, WOAD)
Site safeguard and management
Where possible, ensure that all occupied habitat is appropriately managed by 2008, for example through SSSI or agri-environment scheme management agreements. (ACTION: CCW, NE, FC, MAFF, WOAD)
Where possible, ensure that existing populations do not become fragmented by management practices or development. (ACTION: CCW, NE, FC, LAs, MAFF, WOAD)
Where possible, increase the available habitat at known sites and adjacent areas, and attempt to link up existing fragments of habitat. (ACTION: CCW, NE, FC, MAFF, WOAD)
Restore suitable habitats in the English part of former range, initially concentrating on areas close to existing populations (south-east, south-west, eastern and midland England). (ACTION: NE)
Ensure that the habitat requirements of this species are taken account of in relevant development policies, plans and proposals. (ACTION: CCW, NE, LAs)
Ensure that the species is included in site management documents for all relevant SSSIs. (ACTION: CCW, NE)
Species management and protection
Consider reintroducing the silver-studded blue to a series of sites within its former range. (ACTION: CCW, NE)
Advisory
Advise landowners and managers of the presence of the silver-studded blue and the importance of beneficial management for its conservation. (ACTION: CCW, NE, MAFF, WOAD)
As far as possible, ensure that all relevant agri-environment project officers, and members of regional agri-environment consultation groups, are advised of locations of this species, its importance, and the management needed for its conservation. (ACTION: CCW, NE, MAFF, WOAD)
Future Research and Monitoring
Undertake surveys to determine the current status of the silver-studded blue. (ACTION: CCW, NE)
Conduct targeted autecological research to inform habitat management. (ACTION: CCW, NE)
Collate transect and management data from all monitored sites (in addition to Butterfly Monitoring Scheme sites) annually, and calculate an annual index to compare trends on individual sites. Review and extend series of monitored sites if necessary. (ACTION: CCW, NE)
Pass information gathered during survey and monitoring of this species to a central database for incorporation in national and international databases. (ACTION: CCW, NE)
Communications and Publicity
Promote opportunities for the appreciation of the silver-studded blue and the conservation issues associated with lowland heathland and lowland calcareous grassland. (ACTION: CCW, NE)
Links with other action plans
None given.
Publication details
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume IV: Invertebrates (March 1999, Tranche 2, Vol IV, p379)
Related links
ARKive Visit the ARKive website to view images and further information relating to this species