Coenagrion mercuriale - Southern Damselfly

Southern Damselfly (male)
Male

Southern Damselfly (tandem pair)
Pair in tandem

Exuvia
Exuvia (male, side view)

Description
Length: 29mm

The Southern Damselfly, Coenagrion mercuriale, is one of five members of the genus Coenagrion currently to be found in the British Isles (two others have gone extinct in the last 40 years) and one of eleven members of the family Coenagrionidae. Together with Common Blue Damselfly (Enallagma cyathigerum) and White-legged Damselfly (Platycnemis pennipes), the Coenagrion species constitute the blue damselflies, which are all blue and black in colour. Male Southern Damselflies can only be identified from examination of the anal appendages, though the mercury mark on the second abdominal segment is a useful guide. Female Coenagrion species are very similar making them difficult to identify. Adults are on the wing from mid May to August. The flight is weak and low; they stay close to the breeding site and do not appear to disperse easily to colonise new areas. Low shrubs and Juncus spp. are used for perching, roosting and feeding forays.C. mercuriale mercury mark

The picture on the right shows a close-up of the mercury mark from a Southern Damselfly population in the New Forest. Copyright Environment Agency, 1999.

Eggs are laid in submerged tissues of aquatic and emergent vegetation and the plant dwelling larvae usually take two years to mature. The larvae are distinctive in that they have very small, un-patterned caudal lamellae.

Habitat
In the UK the Southern Damselfly is primarily a species of base-rich runnels and streams often within acid heathland areas. However, it also occurs on water meadows in the flood plains of two chalk rivers, a habitat said to be more typical of many continental sites. At breeding sites the water is typically shallow and slow-flowing over a gravel or marl bed with patches of organic detritus. It may be that a more or less constant, relatively high, water temperature in winter in the spring-fed sites is particularly important in determining site suitability.

Status and Distribution
The Southern Damselfly is a rare species in the UK. Although it is living on the extreme north-western fringe of its European range, it is believed that up to 25% of the global population of this species occurs in the UK. Its two main strongholds are in the New Forest, Hampshire and the Preseli mountains, Pembrokeshire. Smaller colonies are found in Devon, Dorset, Anglesey, Gower, Oxfordshire and on the flood plains of the Test and Itchen rivers in Hampshire. There are old records from Cornwall and Somerset and elsewhere in Devon, Dorset and South Wales. The range of the species has contracted in the last thirty years.

The main factor thought to be influencing the decline of the species is the removal of grazing animals that maintain the open nature of the species' breeding sites. Other potential threats are abstraction of water, leading to a lowering of the water table, drainage due to agricultural and forestry pressures, and excessive nutrient enrichment from the runoff of nitrogenous fertilisers from adjacent agricultural land. Isolation and scarcity of habitats is a cause for concern.

Beyond the UK, the Southern Damselfly's distribution is in Western Europe, principally around the western Mediterranean, including Northwest Africa. It has vanished or is on the edge of extinction in 7 countries situated along the northern boundaries of its distribution (Belgium, The Netherlands, Luxembourg, Slovenia, Romania, Poland, Austria) and is declining in 3 others (UK, Germany, Switzerland). A world distribution map of Southern Damselfly can be found in Askew, R. R. (1998), The Dragonflies of Europe, Harley Books.

A very useful account of the ecology of the Southern Damselfly is available to download as a .pdf document.

This species is protected under Schedule 5 of the 1981 Wildlife and Countryside Act, as amended, which protects it against a variety of factors including killing or selling of individuals and damage or destruction of habitat. In Great Britain this species is classified as Rare (category 3) on the Red Data Book List (it also features on the red list of other Countries in Europe), and it is a British Dragonfly Society "Key Species".

It is also listed in Appendix II of the Berne Convention and Annex II of the EC Habitats Directive, which is transposed into UK law through the Conservation (Natural Habitats &c.) Regulations (1994), commonly referred to as the Habitats Regulations. Under the Regulations sites of significant ecological importance within a European context for their habitats and/or species populations have been proposed as Special Areas of Conservation (SAC). In the UK there are more than 10 candidate SACs with one of the qualifying criteria being the presence of Southern Damselfly.

The UK Biodiversity Steering Group published the UK Biodiversity Action Plan (BAP) in 1995. This identified the Southern Damselfly as a priority species for conservation action and included (Volume 2, page 132) a Species Action Plan (SAP) for the species. For more information visit www.ukbap.org.uk. The UK BAP accords with and implements the UN Convention on Biological Diversity, signed at the Rio Earth Summit in 1992. Its overall goal is to conserve and enhance biological diversity within the UK and to contribute to the conservation of global biodiversity.

To co-ordinate implementation of the UK Southern Damselfly SAP a Steering Group was established in 1997. This partnership of organisations comprises: Environment Agency (Contact Point), The Wildlife Trusts (Lead Partner), Natural England - formerly English Nature, Countryside Council for Wales and British Dragonfly Society. Subsequently academics from Liverpool University were co-opted onto the Group.

The published objectives of the Southern Damselfly UK SAP can be found on the UKBAP site. However, it should be borne in mind that the objectives and targets are being revised and may not be updated on the website until Spring 2007

Many efforts to conserve the Southern Damselfly predate the publication of the Species Action Plan (SAP), and much of that work has been initiated and carried out by BDS members, often at their own expense and time. The purpose of the SAP is to provide a framework through which to provide co-ordinated direction to this on-going and future work and to attract and focus new resources to achieving the range of actions identified in the Plan.

The species has undoubtedly benefited from the positive habitat management, surveys and monitoring by bodies such as RSPB and National Trust, and in recent years the SAP has inspired others such as the Forestry Commission, Dartmoor National Park Authority and many others to carryout their own works on Southern Damselfly sites. For example, the MoD and English China Clay have worked in close partnership with EA, EN and RSPB to manage and monitor the Povington Ranges in Dorset. In that respect the SAP is already becoming a great success, the renewed habitat management efforts and new resources building upon the long-standing surveys and monitoring done by BDS volunteers.

Distribution map from the National Biodiversity Network Gateway (opens in new window).

Similar species
This species is easily confused with the other members of the genus Coenagrion and with the Common Blue Damselfly. Look at S2 (on the males) for distinguishing characters. Southern Damselfly is quite small compared with other similar species and will only be found flying in full sunshine in the hottest part of the day. The females can be particularly tricky to distinguish apart.

Monitoring

BDS observers have a vital role to play in this work. The Steering Group recommends that surveillance transects should be undertaken annually, and looks to the BDS to help achieve this. It is highly desirable that all known sites are checked, at least for presence/absence, on a rolling six-year programme and that as many sites as possible are monitored by transect annually. It is also vital that the data be captured centrally, and regularly, so as to be of most use.

Guidance on monitoring methodology is available in leaflet published by the Steering Group, and is also set out in the BDS Dragonfly News, No.39, Spring 2001, and has been considerably updated in this .pdf document.

Data should be sent to Dave Smallshire annually (his contact details can be found in the BDS list of dragonfly recorders), and any feedback on analysis of data will normally be through the BDS Journal.

How you can help

Contact Katharine Parkes (BDS Conservation Officer)

Will anyone currently covering Southern Damselfly sites, or willing to check them on an annual basis, or willing to undertake a weekly transect, please contact Dave or Caroline.

"Champion" needed

An important part of the UK BAP is the involvement of the private sector as "Champions"; providing commercial sponsorship to the process. It is an opportunity for private sector interests to demonstrate their environmental commitment. The Southern Damselfly needs a Champion/or Champions to provide modest sponsorship to implement parts of the BAP. A Champion would be entitled to utilise the UK Biodiversity logo and engage in other promotional activities at a local and national level. Interested parties should contact Tim Sykes or jerveritt@wildlife-trusts.cix.co.uk.

Tim Sykes - June 2002

Further recommended reading

Askew R. R. 1988. The Dragonflies of Europe. Harley Books.

Brook S. 1997. Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland. British Wildlife Publishing.

Hammond C. O. 1983. The Dragonflies of Great Britain and Ireland. 2nd Edition. Harley Books.

Biodiversity: The UK steering Group Report. 1995. Volume 2: Action Plans. London. HMSO.

Merritt R., Moore N. W. and Eversham B. C. 1996. Atlas of the Dragonflies of Britain and Ireland. ITE Research Publication no. 9. London HMSO.

Smallshire D, & Swash A. (2004). Britain's Dragonflies. WildGuides.

Other useful documents to download

Web Sites Links:

This page is summarised from two documents, both of which you can download in Microsoft Word format:
The Southern Damselfly - August 2001 (approx. 280 KBytes)
The Southern Damselfly - Update - June 2002 (approx. 70 KBytes)