Eidda Pastures

Site of Special Scientific Interest · 53.0368, -3.7432

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Coastal

Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.

Geology & landscape

Landscape processes: Coastal

Description

Description Porth Diana is part of the nationally important coastal heath on the west coast of Holy Island. This heath, which is very exposed to westerly winds, is developed on a rocky escarpment. It is short in stature and typically consists of ling Calluna vulgaris, bell heather Erica cinerea, western gorse Ulex gallii and creeping willow Salix repens. The locally rare, dyer's greenweed Genista tinctoria occurs in its only extant Anglesey site here. A distinctive assemblage of plants occurs on the thin soils around the bare rock areas. Annual rockrose Tuberaria guttata occurs in great abundance here. Associated species include spring squill Scilla verna, English stonecrop Sedum anglicum, birdsfoot Ornithopus perpusillus heath pearlwort Sagina subulata and early hairy grass Aira praecox. Tuberaria occurs in only eight localities in Britain, seven of the others being in Anglesey and one in the Lleyn. Of the seven Anglesey sites, six are on Holy Island. The population of Tuberaria at Porth Diana appears to be the largest of any of the sites.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
early hair grass Aira praecox VU grass poaceae
dyer's greenweed Genista tinctoria LC herb fabaceae
bird's foot Ornithopus perpusillus LC herb fabaceae
heath pearlwort Sagina subulata LC herb carophyllaceae
spring squill Scilla verna LC herb liliaceae
English stonecrop Sedum anglicum LC herb crassulaceae
spotted rock rose Tuberaria guttata VU herb cistaceae
western gorse Ulex gallii LC shrub leguminosae
bell heather or ling Calluna vulgaris NT shrub dwarf ericaceae
bell heather Erica cinerea NT shrub dwarf ericaceae
creeping willow Salix repens NT tree shrub salicaceae

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

SpeciesStatusVia host-plant
Dark bordered beauty
Epione vespertaria
Endangered Salix repens
The lappet
Gastropacha quercifolia
Endangered Salix spp.
Shoulder-striped clover
Heliothis maritima
Endangered Calluna vulgaris, Erica cinerea
Scarce vapourer
Orgyia recens
Endangered Salix spp.
The sprawler
Asteroscopus sphinx
Vulnerable Salix spp.
Broom moth
Ceramica pisi
Vulnerable Calluna vulgaris
Scarce chocolate-tip
Clostera anachoreta
Vulnerable Salix spp.
Mottled umber
Erannis defoliaria
Vulnerable Salix spp.
Satyr pug
Eupithecia satyrata
Vulnerable Calluna vulgaris, Salix spp.
Grayling
Hipparchia semele
Vulnerable Aira praecox
True lover's knot
Lycophotia porphyrea
Vulnerable Calluna vulgaris, Erica cinerea
The lackey
Malacosoma neustria
Vulnerable Salix spp.
Silver studded blue
Plebejus argus
Vulnerable Calluna vulgaris, Erica cinerea, Ulex spp.
Lead belle
Scotopteryx mucronata
Vulnerable Genista tinctoria
Pale eggar
Trichiura crataegi
Vulnerable Calluna vulgaris, Erica cinerea, Salix spp.
Flounced chestnut
Agrochola helvola
Near Threatened Calluna vulgaris, Salix spp.
Beaded chestnut
Agrochola lychnidis
Near Threatened Salix spp.
The sallow
Cirrhia icteritia
Near Threatened Salix spp.
Dingy mocha
Cyclophora pendularia
Near Threatened Salix repens
Grey scalloped
Dyscia fagaria
Near Threatened Calluna vulgaris, Erica cinerea
Large thorn
Ennomos autumnaria
Near Threatened Salix spp.
Autumnal rustic
Eugnorisma glareosa
Near Threatened Calluna vulgaris, Erica cinerea, Salix repens
Grey pug
Eupithecia subfuscata
Near Threatened Salix spp.
Double dart
Graphiphora augur
Near Threatened Salix spp.
Weaver's wave
Idaea contiguaria
Near Threatened Calluna vulgaris

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities

H11 — Lowland dry heath

Calluna vulgaris-Carex arenaria heath

Matches 6 species from the description above: Aira praecox, Calluna vulgaris, Erica cinerea, Salix repens, Sedum anglicum, Ulex gallii

Salix repens, Empetrum nigrum subsp.nigrum, Calluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Ulex gallii, Rosa spinosissima, Carex arenaria, Luzula campestris, Pohlia nutans, Campylopus introflexus, Ceratodon purpureus, Dicranum scoparium, Racomitrium canescens sens.lat., Hylocomium splendens, Hypnum jutlandicum, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus triquetrus, Polytrichum juniperinum, Polytrichum piliferum, Lophocolea bidentata, Ptilidium ciliare, Hypogymnia physodes, Cladonia arbuscula, Cladonia coccifera, Cladonia crispata, Cladonia floerkeana, Cladonia foliacea, Cladonia furcata, Cladonia gracilis, Cladonia impexa, Cladonia pyxidata, Cladonia rangiferina, Cladonia rangiformis, Cladonia subcervicornis, Cladonia uncialis, Cornicularia aculeata, Peltigera canina, Hypochaeris radicata, Jacobaea vulgaris, Pilosella officinarum, Teesdalia nudicaulis, Campanula rotundifolia, Jasione montana, Cerastium fontanum, Sedum anglicum, Lotus corniculatus, Ononis repens, Trifolium repens, Thymus praecox, Rumex acetosella, Potentilla erecta, Galium saxatile, Galium verum, Viola riviniana, Agrostis capillaris, Aira caryophyllea, Aira praecox, Ammophila arenaria, Anthoxanthum odoratum, Deschampsia flexuosa, Festuca ovina, Poa pratensis

H7 — Hard cliff and cliff slope, Lowland dry heath

Calluna vulgaris-Scilla verna heath

Matches 6 species from the description above: Aira praecox, Calluna vulgaris, Erica cinerea, Salix repens, Scilla verna, Sedum anglicum

Salix repens, Empetrum nigrum subsp.nigrum, Calluna vulgaris, Erica cinerea, Erica tetralix, Erica vagans, Juniperus communis, Ulex europaeus, Carex caryophyllea, Carex flacca, Carex nigra, Carex panicea, Carex pulicaris, Carex serotina, Luzula campestris, Luzula multiflora, Selaginella selaginoides, Hypnum cupressiforme, Frullania tamarisci, Cladonia chlorophaea, Cladonia rangiformis, Daucus carota, Achillea millefolium, Hypochaeris radicata, Leontodon saxatilis, Leucanthemum vulgare, Scorzoneroides autumnalis, Serratula tinctoria, Jasione montana, Succisa pratensis, Cerastium diffusum, Cerastium fontanum, Silene uniflora, Sedum anglicum, Anthyllis vulneraria, Astragalus danicus, Genista pilosa, Lotus corniculatus, Trifolium repens, Centaurium erythraea, Thymus praecox, Scilla verna, Dactylorhiza purpurella, Euphrasia officinalis, Plantago coronopus, Plantago lanceolata, Plantago maritima, Armeria maritima, Polygala serpyllifolia, Polygala vulgaris, Rumex acetosa, Primula vulgaris, Filipendula vulgaris, Potentilla erecta, Galium verum, Viola riviniana, Agrostis capillaris, Agrostis stolonifera, Aira caryophyllea, Aira praecox, Anthoxanthum odoratum, Dactylis glomerata, Danthonia decumbens, Festuca ovina, Festuca rubra, Holcus lanatus, Koeleria macrantha, Molinia caerulea, Nardus stricta, Chara curta

H8 — Hard cliff and cliff slope, Lowland dry heath, Upland dry heath

Calluna vulgaris-Ulex gallii heath

Matches 5 species from the description above: Aira praecox, Calluna vulgaris, Erica cinerea, Scilla verna, Ulex gallii

Calluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Ulex europaeus, Ulex gallii, Carex binervis, Carex caryophyllea, Carex flacca, Carex pilulifera, Campylopus flexuosus, Dicranum scoparium, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus squarrosus, Polytrichum juniperinum, Polytrichum piliferum, Cladonia impexa, Cladonia squamosa, Hypochaeris radicata, Jasione montana, Lotus corniculatus, Hypericum pulchrum, Teucrium scorodonia, Thymus praecox, Scilla verna, Linum catharticum, Pedicularis sylvatica, Digitalis purpurea, Plantago lanceolata, Plantago maritima, Polygala serpyllifolia, Rumex acetosella, Potentilla erecta, Poterium sanguisorba, Rubus fruticosus agg., Galium saxatile, Galium verum, Viola lactea, Viola riviniana, Agrostis capillaris, Agrostis curtisii, Agrostis stolonifera, Agrostis vinealis, Aira praecox, Anthoxanthum odoratum, Avenula pubescens, Brachypodium sylvaticum, Dactylis glomerata, Danthonia decumbens, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Holcus lanatus, Molinia caerulea, Nardus stricta, Pteridium aquilinum, Chara curta

H4 — Lowland dry heath, Lowland wet heath, Upland dry heath

Ulex gallii-Agrostis curtisii heath

Matches 4 species from the description above: Calluna vulgaris, Erica cinerea, Salix repens, Ulex gallii

Salix repens, Calluna vulgaris, Erica ciliaris, Erica cinerea, Erica tetralix, Erica vagans, Vaccinium myrtillus, Ulex gallii, Carex binervis, Carex flacca, Carex montana, Carex panicea, Carex pilulifera, Trichophorum cespitosum, Juncus squarrosus, Luzula multiflora, Pohlia nutans, Campylopus flexuosus, Campylopus introflexus, Dicranum scoparium, Leucobryum glaucum, Racomitrium lanuginosum, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus squarrosus, Polytrichum juniperinum, Calypogeia fissa, Calypogeia muelleriana, Cephalozia bicuspidata, Diplophyllum albicans, Lophocolea bidentata, Hypogymnia physodes, Cladonia arbuscula, Cladonia chlorophaea, Cladonia coccifera, Cladonia crispata, Cladonia fimbriata, Cladonia floerkeana, Cladonia furcata, Cladonia impexa, Cladonia subcervicornis, Cladonia uncialis, Cuscuta epithymum, Lotus corniculatus, Thymus praecox, Pedicularis sylvatica, Polygala serpyllifolia, Polygala vulgaris, Potentilla erecta, Galium saxatile, Viola lactea, Agrostis canina, Agrostis capillaris, Agrostis curtisii, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Molinia caerulea, Nardus stricta, Pteridium aquilinum

H2 — Lowland dry heath

Calluna vulgaris-Ulex minor heath

Matches 3 species from the description above: Calluna vulgaris, Erica cinerea, Ulex gallii

Pinus sylvestris, Sorbus aucuparia, Calluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Ulex europaeus, Ulex gallii, Ulex minor, Campylopus flexuosus, Dicranum scoparium, Hypnum jutlandicum, Polytrichum juniperinum, Polytrichum piliferum, Kurzia spp., Cladonia arbuscula, Cladonia chlorophaea, Cladonia coccifera, Cladonia fimbriata, Cladonia furcata, Cladonia impexa, Cuscuta epithymum, Genista anglica, Potentilla erecta, Rubus fruticosus agg., Agrostis canina, Agrostis curtisii, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Molinia caerulea, Pteridium aquilinum

H1 — Lowland dry heath

Calluna vulgaris-Festuca ovina heath

Matches 2 species from the description above: Calluna vulgaris, Erica cinerea

Calluna vulgaris, Erica cinerea, Erica tetralix, Ulex europaeus, Carex arenaria, Dicranella heteromalla, Dicranum scoparium, Hylocomium splendens, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Polytrichum juniperinum, Ptilidium ciliare, Hypogymnia physodes, Cladonia arbuscula, Cladonia coniocraea, Cladonia fimbriata, Cladonia furcata, Cladonia impexa, Cladonia macilenta, Cladonia pyxidata, Cladonia squamosa, Cladonia tenuis, Cladonia uncialis, Cornicularia aculeata, Jacobaea vulgaris, Campanula rotundifolia, Cerastium fontanum, Teucrium scorodonia, Rumex acetosella, Galium saxatile, Agrostis capillaris, Deschampsia flexuosa, Festuca ovina, Holcus lanatus, Pteridium aquilinum

H3 — Lowland dry heath, Lowland wet heath

Ulex minor-Agrostis curtisii heath

Matches 2 species from the description above: Calluna vulgaris, Erica cinerea

Quercus robur, Calluna vulgaris, Erica ciliaris, Erica cinerea, Erica tetralix, Ulex europaeus, Ulex minor, Carex pilulifera, Schoenus nigricans, Campylopus brevipilus, Campylopus flexuosus, Leucobryum glaucum, Hypnum jutlandicum, Polytrichum juniperinum, Kurzia spp., Hypogymnia physodes, Cladonia arbuscula, Cladonia coccifera, Cladonia crispata, Cladonia floerkeana, Cladonia impexa, Cladonia pyxidata, Cladonia uncialis, Cuscuta epithymum, Hypericum pulchrum, Polygala serpyllifolia, Potentilla erecta, Viola lactea, Agrostis curtisii, Danthonia decumbens, Molinia caerulea, Pteridium aquilinum, Zygogonium ericetorum

M14 — Lowland dry heath, Upland wet heath

Schoenus nigricans-Narthecium ossifragum mire

Matches 2 species from the description above: Calluna vulgaris, Ulex gallii

Pinus sylvestris, Calluna vulgaris, Erica tetralix, Myrica gale, Ulex gallii, Carex panicea, Eriophorum angustifolium, Rhynchospora alba, Schoenus nigricans, Eleocharis multicaulis, Juncus acutiflorus, Juncus bulbosus, Ctenidium molluscum, Hypnum jutlandicum, Scorpidium revolvens, Scorpidium scorpioides, Sphagnum auriculatum, Sphagnum palustre, Sphagnum papillosum, Sphagnum subnitens, Sphagnum tenellum, Calypogeia fissa, Kurzia pauciflora, Ordontoschisma sphagni, Aneura pinguis, Riccardia multifida, Drosera intermedia, Drosera rotundifolia, Pinguicula lusitanica, Narthecium ossifragum, Pedicularis sylvatica, Polygala serpyllifolia, Anagallis tenella, Potentilla erecta, Molinia caerulea