La Mare au Seigneur

St Ouen's Pond is situated to the west of the island within the St Ouen’s Bay ‘Special Place’(area designated as Les Mielles). The reserve is some 48hectares (266 vergees) in size and contains a rich tapestry of habitats including open water, reed-bed, fen, wet meadows, dune grasslands, rank grassland and scrub land. Principally it is a wetland reserve and because of the rich habitat matrix, the reserve proves extremely appealing to both flora and fauna. As such the reserve is recognised to be of high conservation importance and has been proposed as being a Site of Special Interest (SSI).

History

St Ouen's Pond is the colloquial name for La Mare au Seigneur which is Jersey French for ‘the pond/marsh of the Seigneur (a local noble)’. The first known record of the pond dates back to 1309 at which time the pond was used to stock fish for the Seigneur of St Ouen. Up until World War II (1939-45) the pond was still used this way with the surrounding land used as a hunting ground by the Seigneur. The reed-bed was well cropped and used for thatching and bedding purposes and at this time it was possible to access the water’s edge in most places.

The German occupation of Jersey in World War II resulted in the construction of large scale defences in St Ouen’s Bay. At the pond two large anti-tank ditches were constructed to the north and south of the main pond. These ditches still exist today and are now known as the north and south canals.

The meadows and grasslands surrounding the pond have always been used for agricultural purposes. Fields have been separated by walls and hedgerows. Farming has predominantly been grazing and hay cropping depending on the season. This practice over the centuries has enabled a rich meadow flora to develop. The Pond and the majority of the surrounding land was purchased by the National Trust for Jersey from 1972 onwards and under the Trust's guardianship has become a popular nature reserve.

Flora

The reserve has a rich diversity of wetland and fen vegetation. The high biodiversity found within the confines of the reserve is due largely to its geographical position, lying at the northern margin of many Mediterranean plant species and at the southern margin of many North European plant varieties. Consequently the plant communities are viewed as being significant as a whole.

There is a remarkably varied flora surrounding the pond and much of the wetland flora is now, or always has been, rare elsewhere in the island. These species include Parsley Water-dropwort (Oenanthe lachenlii), Tubular Water-dropwort, Strawberry Clover, Early-Marsh Orchid and Brookweed. Water Mint, Common Fleabane (Pulicaria dysenterica) and Water Forget-me-not are amongst the common species found.

The drier, sandy areas to the west and the north-west of the pond support species which are at, or near, the northern limit of their range. These include native Jersey Thrift and naturalised Rough Star-thistle. Rare species such as Small Hare’s-ear and Bastard Toadflax can be seen amongst the frequent Lady’s Bedstraw, Common Restharrow, Wild Thyme, Common Centaury, Pyramidal Orchid and Common Bird’s-foot-trefoil.

Fauna

Mammals
Land use pressures and the fact that Jersey is an island have resulted in a limited mammal diversity. Jersey has even fewer indigenous species left as the majority of existing mammal species have been introduced into the island by man. The reserve at La Mare au Seigneur does however provide several habitat types which support substantial mammal numbers. Abundant populations of Field Mice, House Mice, Jersey Bank Voles, shrew varieties, rabbit, polecats and brown rats are present within the reserve. At dusk it is also possible to see Pipistrelle, Nathusius Pipistrelle and Grey long-eared bats within the reserve.

Birds
The site is regarded as being an important site for birdlife in the island due to its rich habitat matrix attracting a high variety of species. The reserve has several resident and breeding species which are listed in the UK red and amber lists. In 2002 a pair of Marsh Harriers bred for the first time at the reserve. The Marsh Harrier is listed as a Red Data Species ( of high conservation concern) in the UK primarily because of an historical decline of the UK population. Other breeding birds of particular importance include: Cetti’s Warbler, Skylark, Northern Lapwing, Reed Warbler, Bearded Tit, Barn Owl and Reed Bunting. It is also a valued stopover for passage and wintering birds, in particular the Bittern and Aquatic Warbler. Since 1992, 188 species of bird (cf. Bird Species List) have been recorded at the site and with changes in the global climate further species are appearing each year.

Reptiles and Amphibians
Jersey has relatively few native reptile and amphibian species. Only 7 species are known to exist within the island, but 5 of these species can be found at La Mare au Seigneur. All 5 species are listed as protected wild animals under Article 2(1) of the Conservation of Wildlife (Jersey) Law 2000.

Species found at La Mare au Seigneur: Common Toad (Bufo bufo), Palmate Newt (Triturus helveticus), Green Lizard (Lacerta viridis), Slow-worm (Anguis fragilis), Grass Snake (Natrix natrix)

Site Management

Management considerations at the pond primarily reflect the threats to the ongoing conservation and sustainability of the reserve. These threats include:

• Nutrient enrichment due to farm runoff and waterfowl excretia.
• Eutrophication of pond in summer months due to nutrient enrichment
• Water abstraction outside National Trust land potentially could lower water table, leading to pond level fluctuations, drying out of pond margins and possible saltwater intrusion and to an increase in nutrient loading.
• Hazard risk - fire and pollution
• Spread of pernicious weeds including Thistle, Japanese Knotweed and Hemlock Water Dropwort
• Growth of willow in reed beds
• Introduction of foreign species presenting a threat to indigenous species e.g. Black Swan, polecat, feral cats, terrapins
• Loss of grazing due to decline in farming industry
• Human interference by way of vandalism, rubbish and path erosion.
• Area would become a brackish environment if coastal policy is changed to manage retreat of sea wall defences
• Sedimentation of shallow water areas
• Rapid reed bed expansion swallowing rare fringe plant species
• Global warming could lead to new species colonising the area, with traditional species becoming scarce

To combat such factors the reserve receives an intensive annual work program so that the high conservation aspect remains unharmed. Rare and threatened species are monitored. Vegetation levels are kept in check through a combination of grazing and hay cutting. Weed species are controlled and removed. Reed-bed expansion versus wet meadow is controlled through an annual cutting regime and Pond water levels are regularly monitored.

Visitor Access and Facilities

Due to the environmental sensitivity of the reserve access is restricted. There are currently two bird hides within the reserve, located:

• to the west of the reserve along La Grande Route des Mielles opposite the Discovery Bay Apartments,
• to the south of the reserve accessed at the gravel lay-by opposite ‘the Splash’.

These bird hides are open to the public throughout the year. In addition guided walks are held from time to time.

La Mare au Seigneur is situated alongside a main road (La Grande Route des Mielles) and ample parking is available nearby. There is also a bus stop on the main road at the reserve.