The wart-biter is a species of calcareous grassland, although one extant UK colony occupies a heathland/grassland site. The species requires a finely balanced habitat mosaic: bare ground/short turf, into which eggs are laid; grass tussocks, amongst which older nymphs and adults conceal themselves from predators; and a sward rich in flowering forbs and invertebrates, which provide nutrition. The species is thermophilous, and tends to occur on sites with a southerly aspect. Eggs are laid into the soil and persist underground over two winters, hatching in mid to late April. There are seven nymphal instars, and the adult stage is usually attained in July. Oviposition occurs from August until around early October, when the adults die off. Although regarded as the same species, the wart-biter appears to differ slightly in the UK from individuals found in continental populations.
Records suggest that the species has been very localised in southern England since at least the early 1800s. Former records exist for Hampshire and the Isle of Wight, and a number of historic colonies have been lost from within the current range. There are currently five populations, two in East Sussex and one each in Dorset, Wiltshire and Kent (the latter arising from a recent reintroduction). Numbers of individuals vary considerably between years, but all extant populations are small. The largest is estimated to contain 2000 adults in peak years, but colonies often contain only 20-50 adults, or fewer in poor years. The species is widespread in central and southern Europe, but appears to be declining in parts of this range.
In Great Britain this species is classified as Vulnerable. It is given full protection under Schedule 5 of the Wildlife and Countryside Act 1981.
Current factors causing loss or decline
Inappropriate grassland management, leading to loss of habitat quality and small population sizes, is the major threat to this species.
Predation, particularly by birds, is a significant problem at some sites.
A programme of research on this species and its habitat requirements, on behalf of NE, has been in operation since 1987. This has involved surveys of historical, extant and potential (re)introduction sites, population monitoring, formulation of habitat management recommendations and a (re)introduction programme.
A captive breeding programme for this species has been operating at the Invertebrate Conservation Centre, London Zoo (on behalf of NE), since 1993/94.
The sites of the five current populations comprise two NNRs, two SSSIs and one County Trust Nature Reserve.
A species action plan, commissioned by NE, was completed in 1997.
Action plan objectives and targets
Maintain viable populations at all known sites
Enhance the population size at all known sites by 2005.
Restore populations of the wart-biter to at least three sites by 2005.
Attain long-term viable populations at four sites by 2005.
Secure the future of the species in England by providing a minimum of 10 populations across its known range by 2010, provided that suitable habitat and (re)introduction stock are available.
Proposed actions with lead agencies
Policy and legislation
Where appropriate, include the requirements of the species when preparing or revising prescriptions for agri-environment schemes. (ACTION: NE, MAFF)
Site safeguard and management
Where possible, ensure that all occupied and nearby potential habitat is appropriately managed by 2005, for example through SSSI or agri-environment scheme management agreements. (ACTION: NE, MAFF)
Ensure that the habitat requirements of the wart-biter are taken into account in any relevant development policies, plans and proposals. (ACTION: NE, LAs)
Ensure that the species is included in site management documents for all relevant SSSIs. (ACTION: NE).
Consider notifying as SSSIs sites holding key populations of this species, where this is necessary to secure their long-term protection and appropriate management. (ACTION: NE).
Species management and protection
Monitor, and take relevant action against, competitive and predatory species. (ACTION: NE).
(Re)introduce the wart-biter to sites within the former range of the species, where appropriate habitat and site management are available, in order to restore three populations by 2005, and ensure that there are a minimum of 10 populations by 2010. (ACTION: NE).
Advise landowners and managers of the presence of the species and the importance of beneficial management for its conservation. (ACTION: NE)
Future Research and Monitoring
Conduct targeted autecological research to inform habitat management. (ACTION: NE)
Support the continued development of a captive breeding and (re)introduction programme. (ACTION: NE)
Continue to monitor populations and habitat conditions at occupied sites. (ACTION: NE)
Continue a programme of surveys to identify potential sites for (re)introductions. (ACTION: NE)
Pass information gathered during survey and monitoring of this species to a central database for incorporation into national and international databases. (ACTION: NE).
Communications and Publicity
Promote opportunities for the appreciation of this species and the conservation issues associated with its habitat. This should be achieved through articles within appropriate journals, as well as by a publicity leaflet. (ACTION: NE)
Links with other action plans
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume IV: Invertebrates (March 1999, Tranche 2, Vol IV, p445)
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