Ham Hill

Site of Special Scientific Interest · 51.3525, -1.5237

Condition (Natural England)

Favourable (1)
UnitFeatureConditionArea (ha)Assessed
SU332616 Favourable 1.53 2012-12-17

Geology & landscape

Rock Type: Chalk

Birds & fish recorded

Birds

SpeciesSeason
blackcap Unknown
tree pipit Unknown
whitethroat Unknown

Description

Description Ham Hill is a small but remarkable area of chalk grassland supporting a diverse assemblage of plants and a wide variety of associated butterflies. The majority of the site occupies the steep banks of an ancient sunken trackway forming a cutting through a north facing downland ridge lying on the Upper and Middle Chalk. An open, short, herb rich turf with scattered ant hills has developed on the thin soils of the slopes in contrast with the taller vegetation on the flatter areas. Upright brome Bromus erectus is a major component of the lightly grazed sward which also includes sheep's fescue Festuca ovina and quaking grass Briza media and frequent typical downland herbs such as burnet saxifrage Pimpinella saxifraga, salad burnet Poterium sanguisorba, common milkwort Polygala vulgaris and dwarf thistle Cirsium acaule. The less common horseshoe vetch Hippocrepis comosa and squinancywort Asperula cynanchica also occur, while both clustered bellflower Campanula glomerata and autumn gentian Gentianella amarella are abundant. Orchids are exceptionally well represented; the eight species present include frog orchid Dactylorhiza viridis and species of nationally restricted distribution such as burnt orchid Neotinea ustulata and musk orchid Herminium monorchis, the latter of which occurs in large numbers. Both fragrant orchid Gymnadenia conopsea and pyramidal orchid Anacamptis pyramidalis are also numerous. Many chalk associated bryophytes are found including the liverwort Leiocolea turbinata and mosses such as Ctenidium molluscum, Dicranella varia, Weissia microstoma and Entodon concinnus, a rare moss of chalk grassland. A small area of secondary ash Fraxinus excelsior woodland exists to the extreme south of the site and scrub is scattered elsewhere. Shrubs present include frequent blackthorn Prunus spinosa, hawthorn Crataegus monogyna, elder Sambucus nigra and privet Ligustrum vulgare and occasional wayfaring tree Viburnum lantana, dogwood Cornus sanguinea and buckthorn Rhamnus cathartica. This mixed scrub habitat is attractive to a number of bird species including tree pipit, yellowhammer, blackcap and whitethroat. The botanical diversity, varied structure and sheltered nature of the site render it very favourable to a variety of butterflies. Cowslips Primula veris, abundant in the areas of long vegetation, support a colony of the scarce Duke of Burgundy Hamearis lucina. Other species present associated with chalk flora include green hairstreak Callophrys rubi, dingy skipper Erynnis tages, dark green fritillary Argynnis aglaja and the uncommon chalkhill blue Polyommatus coridon.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
yellowhammer Emberiza citrinella LC (Breeding) bird-bunting emberizidae
tree pipit Anthus trivialis LC (Breeding) bird-pipit motacillidae
blackcap Sylvia atricapilla LC (Breeding) bird-warbler sylviidae
whitethroat Sylvia communis Not listed in GB list bird-warbler sylviidae
dark green fritillary Argynnis aglaja Not listed in GB list butterfly nymphalidae
green hairstreak Callophrys rubi LC butterfly lycaenidae
dingy skipper Erynnis tages LC butterfly hesperiidae
Duke of Burgundy Hamearis lucina VU butterfly riodinidae
chalkhill blue Polyommatus coridon VU butterfly lycaenidae
quaking grass Briza media VU grass poaceae
upright brome Bromus erectus Not listed in GB list grass poaceae
sheep's fescue Festuca ovina LC grass poaceae
pyramidal orchid Anacamptis pyramidalis LC herb orchidaceae
squinancywort Asperula cynanchica VU herb rubiaceae
clustered bellflower Campanula glomerata VU herb campanulaceae
dwarf thistle Cirsium acaule VU herb asteraceae
frog orchid Dactylorhiza viridis VU herb orchidaceae
autumn gentian Gentianella amarella LC herb gentianaceae
fragrant orchid Gymnadenia conopsea NT herb orchidaceae
musk orchid Herminium monorchis EN herb orchidaceae
horseshoe vetch Hippocrepis comosa VU herb fabaceae
burnt orchid Neotinea ustulata EN herb orchidaceae
burnet saxifrage Pimpinella saxifraga NT herb apiaceae
common milkwort Polygala vulgaris VU herb polygalaceae
salad burnet Poterium sanguisorba VU herb rosaceae
cowslip Primula veris LC herb primulaceae
top notchwort Leiocolea turbinata Not listed in GB list liverwort jungermanniales
comb moss Ctenidium molluscum LC moss hypnales
variable forklet moss Dicranella varia LC moss dicranales
Montagne's cyinder moss Entodon concinnus LC moss hypnales
dogwood Cornus sanguinea LC shrub cornaceae
hawthorn Crataegus monogyna LC shrub rosaceae
wild privet Ligustrum vulgare LC shrub oleaceae
blackthorn Prunus spinosa LC shrub rosaceae
buckthorn Rhamnus cathartica LC shrub rhamnaceae
elder Sambucus nigra LC shrub caprifoliaceae
wayfaring tree Viburnum lantana LC shrub caprifoliaceae
ash Fraxinus excelsior LC tree oleaceae

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
Figure of eight
Diloba caeruleocephala
Endangered Crataegus spp., Prunus spinosa, Prunus spp.
The lappet
Gastropacha quercifolia
Endangered Crataegus monogyna, Prunus spinosa, Prunus spp., Rhamnus cathartica
Duke of Burgundy
Hamearis lucina
Endangered Primula veris
Scarce vapourer
Orgyia recens
Endangered Crataegus spp., Prunus spinosa
Black hairstreak
Satyrium pruni
Endangered Prunus spinosa
Mouse moth
Amphipyra tragopoginis
Vulnerable Crataegus spp., Poterium sanguisorba
The sprawler
Asteroscopus sphinx
Vulnerable Crataegus spp., Fraxinus excelsior, Prunus spinosa, Prunus spp., Viburnum lantana
Mottled umber
Erannis defoliaria
Vulnerable Crataegus spp., Prunus spinosa
Dingy skipper
Erynnis tages
Vulnerable Hippocrepis comosa
Grayling
Hipparchia semele
Vulnerable Festuca ovina
The lackey
Malacosoma neustria
Vulnerable Crataegus monogyna, Prunus spinosa, Prunus spp.
Pale brindled
Phigalia pilosaria
Vulnerable Cornus sanguinea, Crataegus monogyna, Fraxinus excelsior, Prunus spinosa, Rhamnus cathartica
Silver studded blue
Plebejus argus
Vulnerable Hippocrepis comosa
Grizzled skipper
Pyrgus malvae
Vulnerable Poterium sanguisorba
Brown hairstreak
Thecla betulae
Vulnerable Prunus spinosa
Early moth
Theria primaria
Vulnerable Crataegus monogyna, Prunus spinosa
Pale eggar
Trichiura crataegi
Vulnerable Crataegus monogyna, Prunus spinosa
Flounced chestnut
Agrochola helvola
Near Threatened Crataegus monogyna
Beaded chestnut
Agrochola lychnidis
Near Threatened Crataegus monogyna
Grey chi
Antitype chi
Near Threatened Crataegus monogyna
Garden tiger
Arctia caja
Near Threatened Prunus spinosa
Small heath
Coenonympha pamphilus
Near Threatened Festuca spp.
Large thorn
Ennomos autumnaria
Near Threatened Crataegus spp., Prunus spinosa, Prunus spp.
Dusky thorn
Ennomos fuscantaria
Near Threatened Fraxinus excelsior
Autumnal rustic
Eugnorisma glareosa
Near Threatened Festuca ovina
Grey pug
Eupithecia subfuscata
Near Threatened Crataegus monogyna, Pimpinella saxifraga, Prunus spinosa
White-spotted pug
Eupithecia tripunctaria
Near Threatened Sambucus nigra
Double dart
Graphiphora augur
Near Threatened Crataegus spp., Prunus spinosa
Silver-spotted skipper
Hesperia comma
Near Threatened Festuca ovina
Rosy minor
Litoligia literosa
Near Threatened Festuca ovina
Swallowtail papilio
Papilio machaon
Near Threatened Pimpinella saxifraga

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

W21 — Hedgerow scrub, Mixed scrub

Crataegus monogyna-Hedera helix scrub

Matches 9 species from the description above: Cornus sanguinea, Crataegus monogyna, Fraxinus excelsior, Ligustrum vulgare, Poterium sanguisorba, Prunus spinosa, Rhamnus cathartica, Sambucus nigra, Viburnum lantana

Hedera helix, Salix cinerea, Acer pseudoplatanus, Ilex aquifolium, Betula pendula, Corylus avellana, Fagus sylvatica, Quercus robur, Fraxinus excelsior, Malus sylvestris, Sorbus aria, Taxus baccata, Ulmus glabra, Ulmus procera, Sambucus nigra, Viburnum lantana, Euonymus europaeus, Cornus sanguinea, Juniperus communis, Ligustrum vulgare, Clematis vitalba, Rhamnus cathartica, Crataegus laevigata, Crataegus monogyna, Prunus spinosa, Juncus effusus, Plagiomnium undulatum, Brachythecium rutabulum, Kindbergia praelonga, Rhynchostegium confertum, Tamus communis, Heracleum sphondylium, Torilis japonica, Arum maculatum, Arctium minus, Cirsium arvense, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Stellaria graminea, Stellaria holostea, Stellaria media agg., Calystegia sepium, Mercurialis perennis, Geranium robertianum, Iris foetidissima, Glechoma hederacea, Lamium purpureum, Origanum vulgare, Stachys sylvatica, Teucrium scorodonia, Allium ursinum, Hyacinthoides non-scripta, Circaea lutetiana, Rumex sanguineus, Anemone nemorosa, Ranunculus repens, Fragaria vesca, Geum urbanum, Potentilla sterilis, Poterium sanguisorba, Rosa arvensis, Rosa canina, Rubia peregrina, Rubus fruticosus agg., Galium aparine, Urtica dioica, Viola riviniana, Anisantha sterilis, Arrhenatherum elatius, Brachypodium pinnatum, Brachypodium sylvaticum, Bromopsis erecta, Dactylis glomerata, Elytrigia repens, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris filix-mas

W20 — Montane scrub

Salix lapponum-Luzula sylvatica scrub

Matches 3 species from the description above: Ctenidium molluscum, Dactylorhiza viridis, Festuca ovina

Salix arbuscula, Salix cinerea, Salix lapponum, Salix myrsinites, Salix phylicifolia, Salix reticulata, Empetrum nigrum, Calluna vulgaris, Salix lanata, Vaccinium myrtillus, Vaccinium uliginosum, Carex atrata, Carex bigelowii, Carex binervis, Carex flacca, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Mnium hornum, Philonotis fontana, Plagiomnium undulatum, Rhizomnium punctatum, Dicranum bonjeanii, Dicranum majus, Dicranum scoparium, Fissidens adianthoides, Racomitrium lanuginosum, Calliergonell cuspidatum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Palustriella commutatum, Plagiothecium denticulatum, Plagiothecium undulatum, Pleurozium schreberi, Ptilium crista-castrensis, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Scorpidium revolvens, Thuidium tamariscinum, Atrichum undulatum, Polytrichastrum alpinum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum girgensohnii, Sphagnum palustre, Sphagnum russowii, Sphagnum squarrosum, Sphagnum subnitens, Sphagnum teres, Barbilophozia barbata, Chiloscyphus polyanthos, Diplophyllum albicans, Lophocolea bidentata, Plagiochila porelloides, Ptilidium ciliare, Scapania undulata, Cladonia squamosa, Peltigera canina, Angelica sylvestris, Caltha palustris, Hieraclium spp., Saussurea alpina, Solidago virgaurea, Campanula rotundifolia, Succisa pratensis, Valeriana officinalis, Rhodiola rosea, Vaccinium vitis-idaea, Thymus praecox, Epilobium anagallidifolium, Dactylorhiza viridis, Euphrasia officinalis, Rhinanthus minor, Oxalis acetosella, Oxyria digyna, Polygonum viviparum, Rumex acetosa, Anemone nemorosa, Ranunculus acris, Thalictrum alpinum, Alchemilla alpina, Alchemilla glabra, Filipendula ulmaria, Geum rivale, Galium boreale, Galium saxatile, Saxifraga aizoides, Saxifraga hypnoides, Saxifraga oppositifolia, Saxifraga stellaris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Dryopteris dilatata, Phegopteris connectilis

W22 — Hedgerow scrub, Mixed scrub

Prunus spinosa-Rubus fruticosus scrub

Matches 1 species from the description above: Prunus spinosa

Hedera helix, Acer campestre, Corylus avellana, Ulex europaeus, Prunus spinosa, Plagiomnium undulatum, Brachythecium rutabulum, Eurhynchium striatum, Kindbergia praelonga, Thuidium tamariscinum, Atrichum undulatum, Lophocolea bidentata, Achillea millefolium, Cardamine flexuosa, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Silene uniflora, Stellaria media agg., Mercurialis perennis, Geranium robertianum, Stachys sylvatica, Teucrium scorodonia, Hyacinthoides non-scripta, Oxalis acetosella, Digitalis purpurea, Plantago lanceolata, Veronica chamaedrys, Armeria maritima, Rumex acetosa, Filipendula ulmaria, Geum urbanum, Rosa canina, Rubus fruticosus agg., Rubus idaeus, Galium aparine, Urtica dioica, Viola riviniana, Agrostis capillaris, Brachypodium sylvaticum, Dactylis glomerata, Festuca rubra, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris borreri, Dryopteris filix-mas