Vegetated Sea Cliffs and Soft Rock Undercliff

​The tall vegetated sea cliffs of Hastings Country Park Nature Reserve are of great ecological and geological importance. This is where the High Weald meets the sea and the landslip scar caused by toe and precipitation erosion exposes important geological and paleontological features. The sea cliffs of Hastings are formed from the interlaced Cretaceous sandstones, siltstones, mudstones and clays of the Ashdown Formation, Tunbridge Wells Sand Formation and Wadhurst Clay Formation.

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The constant erosion and deposition of rock and sediment creates an incredibly complex habitat which is one of the most biodiverse in Britain due to its habitat resource complexity and diversity . Landslip scar and landslip debris create large areas of bare ground and create ledges and crevices for cliff nesting birds. Detached blocks of cliff-top habitat form patches of grassland, heathland and scrub on the cliff-face and undercliff. Seepages and trickles caused by groundwater flowing from the cliff-face create freshwater ponds, streams, channels, wet mud, reedbed and marsh. Flower rich grassland develops in more stable areas of undercliff and where the undercliff remains stable for decades, or even centuries, mature scrub and high canopy woodland can develop. Small waterfalls occur where the gill streams flow onto the cliff-face and small caves can also form due to erosion undercutting the cliff.

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Exposure to wind and salt spray also creates a distinct flora dominated by species tolerant of coastal conditions. The supralittoral rocks and splash zone at the base of the cliff can be rich in lichens. The rare lichen Tornabea scutellifera has been recorded on the Hastings Country Park Nature Reserve cliffs in the past but is now considered extinct. There are also specialised invertebrates that occupy this zone including the sea slater Ligia oceanica.

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At the base of the cliffs vegetation dominated by thrift Armeria maritima subsp. maritima, sea carrot Daucus carota subsp. gummifer, rock samphire Crithmum maritimum, sea-beet Beta vulgaris subsp. maritima, restharrow Ononis repens and buck’s-horn plantain Plantago coronopus occurs. At Rock-a-nore patches of the showy hoary stock Matthiola incana are also present. This is a Mediterranean-Atlantic species introduced into Britain many centuries ago and is now naturalised on coastal habitats such as sea cliffs and shingle.

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Matthiola incana (hoary stock)

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This vegetation supports many rare and scarce species of invertebrate such as the Lixinae weevil Lixus scabricollis on its foodplant sea beet and the very rare Hyperinae weevil Hypera ononidis on its foodplant restharrow. The scarce comb-foot spider Episinus truncatus is also common amongst this type of vegetation hanging its web from vegetation overhanging bare ground.

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Up on the undercliff large areas of flower-rich grassland occur carpeted in clovers, vetches and trefoils. This zone is incredibly rich in pollinators due to a dense resource of pollen and nectar surrounded by bare ground and loose sediment which is ideal for ground nesting bees and wasps.

This is an ideal habitat for the long-horned bee Eucera longicornis and a large population occurs here from Rock-a-nore to Covehurst Bay. This large spectacular solitary bee has declined greatly over the last few decades due to the loss of legume-rich grassland adjacent to suitable nesting habitat. Due to its restricted distribution and observable decline it is listed as nationally scarce and as a species of principal importance in England under the NERC Act 2006, Section 41.

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The female specialises in collecting legume pollen mostly from kidney vetch Anthyllis vulneraria and bird’s-foot trefoil Lotus corniculatus on the undercliff here. The males have very long antennae that can exceed body length and dozens can be seen flying around nesting aggregations or nectaring from bramble on the undercliff.

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A considerable diversity of nesting and breeding habitat for pollinators occurs on the undercliff including bare ground, fallen timber, dead gorse stems, reed stems, wet mud and standing freshwater.

Quite a lot of wetland habitat naturally develops on the undercliff. Groundwater moves through the porous sandstone until it hits a layer of clay, mudstone, siltstone or pebble bed and then moves laterally to the cliff-face. These seepages, trickles and springs form marshy ground, wet mud, shallow streams and small but spectacular bodies of standing freshwater. If these pools don’t fill up with rock falls and sediment aquatic, emergent and marginal vegetation will form and can support interesting communities of aquatic invertebrates and amphibians. Large numbers of damselfly and dragonfly breed in these undercliff ponds and the migrant red-veined darter Sympetrum fonscolombii has even been recorded breeding temporarily on the undercliff at Covehurst.

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The wet mud, shallow pools and channels of flowing water that form are important for many species of ground beetle and water beetle. Nationally scarce ground beetles such as Acupalpus flavicollis and Tachys micros have been recorded here. Semi-permanent channels of flowing water which form support the only south-east England population of the rare water beetle Hydraena pygmaea.

A number of rare and scarce moths have been recorded on the undercliff including the Isle of Wight neb Metzneria littorella. The undercliff at Hastings Country Park Nature Reserve was the first site in mainland Britain the species was recorded. Most British records are from the Isle of Wight, hence the common name of the species. The moth’s foodplant is buck’s-horn plantain which grows extensively on the undercliff and cliff-top.

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Other rare species recorded include fleabane bell Epiblema cnicicolana, a rare species whose foodplant is common fleabane Pulicaria dysenterica. The scarce six-belted clearwing Bembecia ichneumoniformis has also been recorded from the undercliff here. This species, whose foodplant is bird’s-foot trefoil Lotus sp., prefers sparse patches of the plant growing over bare ground on the undercliff here and at Galley Hill.

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The dry sunbaked sparsely vegetation ground on the undercliff can be extremely rich in invertebrates providing habitat for thermophilous species such as the ant mimic jumping spider Myrmarachne formicaria and the scarce ant Temnothorax albipennis which nests in cracks and crevices between rocks and sun-baked mud.

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Thistles are also incredibly rich in species in this habitat. The scarce Lixinae thistle weevil Larinus planus was one of the first places to be found in the Hastings and Rye area on the undercliff here. The last British specimens of the spectacular thistle weevil Lixus angustatus were recorded here on the undercliff of Hastings Country Park Nature Reserve but is now considered extinct although could be rediscovered or there is a possibility of recolonisation from the Continent due to the ideal habitat present on the undercliff here.

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The cliffs of Hastings Country Park Nature Reserve also provide breeding habitat for an important assemblage of cliff nesting birds. Of particular interest are the breeding pairs of peregrine Falco peregrinus, raven Corvus corax and black redstart Phoenicurus ochruros. These cliffs were the first place in Britain where the black redstart bred. Now up to five pairs breed in crevices in the cliff-face and under boulders on the undercliff. The song of black redstart males is a distinctive feature of the cliffs here in spring and pairs feeding young near the base of the cliffs is a common sight. Peregrine have been breeding on these cliffs for some time and the adults can be commonly seen hunting over the cliffs or in the town centre. Ravens have only started to nest on these cliffs in recent years and have also recently colonised Sussex at other cliff sites such as Seaford Head.

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Other cliff nesting species include fulmar Fulmarus glacialis, herring gull Larus argentatus, lesser black-backed gull Larus fuscus, cormorant Phalacrocorax carbo, feral pigeon Columba livia domestica, rock pipit Anthus petrosus and rarely starling Sturnus vulgaris and swift Apus apus.

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All the cliff sites between Bexhill and Pett Level are soft rock cliffs composed of sands and clays as opposed to much of the maritime cliff habitat of the south coast which is mainly composed of chalk, limestone and granite. Soft rock cliffs are constantly eroding and collapsing due to precipitation and groundwater erosion rather than toe erosion caused by the sea. This creates extensive areas of undercliff and landslip debris which actually protects the cliff-base from wave erosion.

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The smaller soft rock cliffs of Bulverhythe and Galley Hill are of quite a different nature to the taller vegetated sea cliff of Hastings Country Park Nature Reserve. Glyne Gap marks the division between two geological formations. On the Hastings side the cliffs of Little Galley Hill and Bulverhythe are formed from the sandstone, siltstone and mudstone of the Ashdown Formation. On the Bexhill side the cliffs of Galley Hill are formed of the siltstone, mudstone and sandstone of the Tunbridge Wells Sand Formation.

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These cliff sites are protected from toe erosion by coastal defence works and stable undercliff. This reduces wave energy exposure and salt spray creating a very different cliff base habitat and vegetation. This has led to the stable deposition of loose sand and the formation of sandy coastal grassland and stable vegetated shingle habitat.

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These small cliff sites are amongst the most important sites for ground nesting bees and wasps in the Hastings & Bexhill area. The diversity of species recorded is high, many rare and scarce species occur and the population sizes of the species nesting can reach into the thousands.

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In recent years some very rare species have colonised these cliffs. In 2018 it was suspected that the nationally rare spring plasterer bee Colletes cunicularius and the newly colonised grey-backed bee Andrena vaga were present in this area. In 2019 the breeding of both these species was confirmed with Colletes cunicularius present nesting on Galley Hill and Little Galley Hill and the majority of Andrena vaga nesting within the cliff-face of Little Galley Hill.

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Colletes cunicularius is a nationally rare species that was once confined to the extensive sand dune systems in north-west England and north-west and south Wales where creeping willow Salix repens is the main pollen resource for the species. In recent years the species has started to colonise the south coast, presumably from the near continent, including populations at Brownwich and Chilling Cliffs (Hampshire), Dungeness (Kent), and Rye Harbour (East Sussex) (Else and Edwards 2018). These populations do not seem to be as restricted on pollen choice and have been recorded collecting pollen from a number of willow species Salix spp., Alexanders Smyrnium olusatrum, and winter heliotrope Petasites fragrans in the Hastings area.

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Many other rare and scarce species occur in this area including the carrot mining bee Andrena nitidiuscula, the black mining bee Andrena pilipes and the jewel wasp Hedychrum nobile which has only been recently described as new to Britain. This wasp is a parasitoid of Cerceris digger wasps and the Cerceris rybyensis and C.arenaria nesting at Galley Hill are most likely the hosts of this species.

The deposition of sand has enabled the colonisation of sand nesting species such as the silvery leafcutter bee Megachile leachella and the coast leafcutter bee Megachile maritima. Large numbers of the bee-wolf wasp Philanthus triangulum also nest here and the common spiny digger wasp Oxybelus uniglumis, which is unusual in attaching its fly prey to its sting while locating its nest.

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In spring yellow-legged mining bee Andrena flavipes and cliff mining bee Andrena thoracica nest in the cliff-face in their thousands. Large numbers of hairy-legged flower bee Anthophora plumipes and the species’ cleptoparasite Melecta albifrons also nest in the top layer of the cliff peppering the cliff-face with nest burrows. And in autumn thousands of ivy bee Colletes hederae nest in the cliff-face of both Galley Hill and Little Galley Hill.

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The bees nesting in the cliff and undercliff forage further inland within the gardens and green spaces in Bexhill and Hastings. Cliff mining bees Andrena thoracica can be seen as far inland as Filsham Reedbed and Combe Haven Valley foraging from hemlock water dropwort Oenanthe crocata and hogweed Heracleum sphondylium.

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Key Species:
Birds:

• Black redstart Phoenicurus ochruros,

• Fulmar Fulmarus glacialis,

• Peregrine Falco peregrinus,

• Raven Corvus corax,

• Rock pipit Anthus petrosus.

Insects:

• Cliff mining bee Andrena thoracica,

• Grey-backed mining bee Andrena vaga,

• Lixus angustatus,

• Long-horned bee Eucera longicornis,

• Six-belted clearwing Bembecia ichneumoniformis,

• Small blue Cupido minimus,

• Spring plasterer bee Colletes cunicularius.

Plants:

• Buck’s-horn plantain Plantago coronopus,

• Hoary stock Matthiola incana,

• Rock samphire Crithmum maritimum,

• Sea beet Beta vulgaris subsp. maritima,

• Sea carrot Daucus carota subsp. gummifer,

• Thrift Armeria maritima.