The wildlife and habitats of Avon

The former county of Avon (now divided into the unitary authorities of Bath & North East Somerset, Bristol, North Somerset and South Gloucestershire) is situated in the south-west region of the UK. The area is bordered by the Bristol Channel to the west and the counties of Gloucestershire, Wiltshire and Somerset to the north, east and south respectively.

Ecologically the area is exceptionally diverse for its size, its varied geology resulting in the occurrence of a number of distinct landscape types (some of which are internationally important) supporting different types of wildlife. These include the Cotswolds, the Mendips, the Severn Estuary, the North Somerset Levels & Moors, the Severn Vale, the Gordano Valley and the Avon Gorge.

Altogether around three quarters of the area consists of open countryside, although over 80% of the population live in urban areas. The Trust has always recognised the importance of both urban and rural nature conservation, and works to promote the value of green space to people living in all parts of the Avon area.

The Cotswolds

The Cotswold Hills are designated as an Area of Outstanding Natural Beauty (AONB) - a nationally important landscape. The hills are an outcrop of Oolitic limestone extending from Warwickshire to Bath, through Oxfordshire, Gloucestershire and Wiltshire; they form the eastern strip of the Avon area.

The Cotswolds are characterised by limestone grassland, barley and other arable land, and ancient broadleaved woodland, where traditional management (eg grazing, sustainable timber production) has favoured a diversity of wildlife. These habitats support a number of species which are rare in Britain, for example clustered bellflower (on limestone grassland), shepherd's needle (on arable land) and Bath asparagus (in woodland). However, in the last 60 years more intensive agricultural practices have resulted in significant habitat loss, especially of the limestone grassland. Through our Biodiversity Project we work with landowners in the Cotswolds to promote and advise on land management which can benefit wildlife; this work is currently focusing on declining arable birds and plants.

Brown's Folly • photo: Ross Chamberlain

Brown's Folly nature reserve is characteristic of the southern Cotswolds landscape which forms a dramatic backdrop to Bath. Overlooking the city across a steep-sided valley, this site lies on top of a network of limestone mines (the rock used to build the city) which now supports a nationally important bat population.

The Mendips

The Mendip Hills are also designated as an AONB (see the Cotswolds above), and extend eastwards from the Bristol Channel, across the edges of Somerset and North Somerset, towards Frome in Wiltshire. Like the Cotswolds, the Mendips are formed from limestone but of a harder type - Carboniferous - which produces a different, more varied type of landscape, with open levels, low hills, heathland, plateaux, ridges and steep valleys.

The part of the Mendips which falls within the Avon area is particularly important for its south-facing limestone grassland with maritime influences. At the best sites, such as Hellenge Hill and Walborough , this habitat supports a number of nationally rare plants and invertebrates such as Somerset hair-grass, honewort and spring cinquefoil. Further inland, Dolebury Warren is one of the most dramatic of the Mendip hillforts, with exceptional limestone grassland and heath, steep wooded slopes and fine views over the surrounding countryside. This reserve is also very important for invertebrates, with 35 nationally rare species recorded.

Hellenge Hill

Hellenge Hill was bought by the Trust with the support of the Heritage Lottery Fund. Lying on hard Carboniferous limestone, with shallow soils and rocky outcrops, the site's south-facing slopes overlook the Somerset Levels & Moors, Brent Knoll, and the Bristol Channel.

Severn Estuary

The Severn Estuary runs the length of Avon's coastal boundary, and is an internationally important wildlife habitat. This is reflected in its many designations: Site of Special Scientific Interest; Special Protection Area (under the EU Directive for Conservation of Wild Birds 1992); Natura 2000 site (under the EU Habitats and Species Directive 1992) and Ramsar site (under the Convention on Wetlands of International Importance). It is also being considered for designation as a Special Area of Conservation under the EC Habitats and Species Directive.

The estuary forms one of the most important inter-tidal zones in Britain, supporting a wide variety of habitats. As well as providing feeding grounds for over-wintering and migratory waders and wildfowl (such as dunlin, redshank and ringed plover), it also attracts a variety of migratory fish species (eg salmon, sea trout and twaite), and accommodates a number of rare plants (eg sea clover, sea barley and slender hare's-ear). It is however a fragile environment; its high tidal range carries the risk of flooding and erosion, and there are other threats from development, pollution and dredging for aggregates. To address these issues, local authorities and other organisations on both sides of the estuary (including local wildlife trusts) are preparing an Estuary Management Plan.

Severn Estuary

The Severn Estuary has the second highest tidal range in the world. This produces high tidal scour and harsh conditions for wildlife, but those species that can tolerate this survive in abundance. The estuary's numerous waders attract predators such as peregrine falcons, which can be seen perched on the bridges.

Severn Vale

The Severn Vale is the strip of coastal plain between the Severn Estuary and the Severn Ridge (the ridge running from the Avon Gorge north-east to Thornbury in South Gloucestershire). The land is generally less than 10m above sea level, and lies on estuarine silt on the coast and peat deposits further inland. The character of the Severn Vale is defined by the historic management of the land; the construction of a sea wall and drainage of fields to form improved pasture land has resulted in a landscape of farmed grassland criss-crossed by ditches.

Along the coastline river and stream banks run into mudflats and saltmarsh. This habitat is closely linked to the Severn Estuary; indeed a band of coastline 1 km wide falls under the estuary's designation zone and forms an important wildlife corridor. Further south, where the Vale meets the River Avon at Avonmouth, the landscape is dominated by industrial development. However, even in this built-up area networks of ditches have survived and are still important for wildlife, notably a population of water voles.

Littleton Brick Pits

Littleton Brick Pits nature reserve, although man-made, forms part of an important chain of reedbeds lying close to the Severn Estuary. These reedbeds provide feeding and breeding grounds for migrating birds such as reed warbler.

North Somerset Levels & Moors

The North Somerset Levels & Moors are the northern counterpart to the more widely celebrated Somerset Levels & Moors, and are very similar in terms of landscape character and wildlife value. The area also bears close resemblance to the Severn Vale (see above) and includes the Gordano Valley (see below); essentially they are all part of the same strip of reclaimed wetland lying on alluvial silt and peat.

The Levels & Moors landscape is characterised by flat pasture land drained and enclosed by networks of ditches (known locally as 'rhynes'). The patterns of these ditches reflect different periods of reclamation and enclosure dating back to Roman times. This man-made wetland landscape is ecologically rich, with rivers, rhynes and wet fields supporting a tremendous variety of species, many of which are locally notable or nationally rare. These include plants (marsh marigold, ragged robin), invertebrates (great silver diving beetle, hairy dragonfly), birds (lapwing, snipe) and mammals (otters, water voles). Although modern agricultural improvements and intensive drainage have damaged and continue to threaten the area's nature conservation value, restoration is possible through raised water level management (see Clapton Moor below). The Trust works to protect and promote awareness of this important local landscape through the North Somerset Levels & Moors Project

Gordano Valley

The Gordano Valley forms the northern tip of the North Somerset Levels & Moors (see above), separated from the main part of this landscape by the Tickenham Ridge. It is bound to the north-east by the River Avon, and to the north-west by the Walton Ridge - the coastal ridge stretching from Portishead to Clevedon.

The Valley has developed as a distinct ecological unit, partly because it has a self-contained water catchment area. Its rhynes in particular have developed a unique range of plant, invertebrate and animal communities which are of outstanding wildlife value. For example, the Valley is nationally important for stoneworts. Large parts of the Valley floor are in conservation management, including a National Nature Reserve part-owned by English Nature, and two reserves owned by the Trust - Weston Moor and Clapton Moor. The sides of the Valley are also important in terms of wildlife and local landscape character, supporting bands of semi-natural ancient woodland such as Weston Big Wood , as well as blocks of limestone grassland such as Walton Common

Clapton Moor

Clapton Moor was one of the first reserves purchased by the Trust with support from the Heritage Lottery Fund. Major work has been carried out in order to raise the water levels on the site, creating a suitable habitat on the lower fields for breeding waders such as lapwing, redshank and snipe.

Avon Gorge

The Avon Gorge extends approximately 3 km north-westwards from the edge of Bristol's docks at Hotwells, levelling out before Sea Mills, but with further areas of limestone cliff occurring further downstream as far as Pill.

The Gorge is designated as an SSSI for its geological as well as its wildlife interest, and has also been proposed for designation as a Special Area of Conservation under the European Habitats Directive. It is of international wildlife importance, supporting an exceptional range of plant species including two (Bristol whitebeam and Wilmott's whitebeam) which are not found anywhere else in the world, and another two (Bristol rock cress and Bristol onion) which are not found anywhere else in Britain. The Gorge is also important for invertebrates and for breeding peregrine falcons.

The Avon Gorge is managed by the National Trust on the North Somerset side. On the Bristol side, it is managed by Bristol City Council in partnership with Bristol Zoo, WWF and English Nature as part of a major initiative to secure the wildlife interest of the area and raise awareness of its importance.

Avon Gorge

The Avon Gorge (together with the Clifton Suspension Bridge which spans it) is one of the most famous landmarks in Bristol; few other major cities in the UK can boast such an outstanding wildlife location within its boundaries.

Bristol

Centrally positioned within the Avon area and influenced by the ecologically rich landscapes described above, Bristol supports a surprising diversity of wildlife. Indeed the city was at the forefront of the urban nature conservation movement, and continues to be a major focus for the Trust through the Bristol Wildlife Project , which is run in partnership with Bristol City Council.

A wide range of wildlife sites can be found in Bristol - from the large estates on the edges (such as Ashton Court, Blaise Castle and Stoke Park), to numerous 'green spaces' dotted throughout the city (including parks, gardens, allotments, cemeteries and sports grounds). Important areas of woodland have survived the urban sprawl, for example Badocks Wood, while notable grassland sites include Hawkfield Meadows, Troopers Hill, and the Downs. The rivers Avon, Frome and Trym form important wildlife corridors, as well as wetland habitats in themselves, supporting invertebrates, fish and birds. Lawrence Weston Moor is the only true remaining area of marshland in the Bristol area, while Avonmouth Sewage Treatment Works provides a stopover for many species of wildfowl within a heavily industrial area.

Wildlife can be found in even the most built-up parts of the city, for example on derelict land, road verges and railway embankments. Buildings can support bats and nesting birds, while up to eight species of fern have been recorded growing on walls in the Bristol area.

Brandon Hill

At Brandon Hill in 1980 the Trust carried out a major habitat creation project to develop a nature park in the centre of the city - the first of its kind in a formal park anywhere in the country. Habitats include ponds, a wildflower meadow, a butterfly garden and woodland.