Eyarth Rocks Butterfly Conservation Reserve,

 Craig-adwy-wynt, Denbighshire

                           Site description by John Davis, Senior Conservation Officer, Butterfly Conservation Head Office,

                                                                      and Jan Miller, N.Wales Volunteer Co-ordinator.

The Eyarth Rocks reserve is part of Craig-adwy-wynt (Welsh for 'windy ridge'), which lies between the villages of Llanfair DC and Pwll Glas, about two miles south of Ruthin. It is one of the richest butterfly sites in North Wales: - 32 of the 34 species known to occur in the region have been recorded on this limestone hill-top. Butterfly Conservation completed the purchase of this important new reserve in 2001. Twenty acres of this Site of Special Scientific Interest have been secured thanks to donations raised through the Society’s ‘Save Our Butterflies’ Appeal and a grant from the Countryside Council for Wales. The CODA wildlife Trust donated money towards site management. We are also grateful to the vendors, Mr and Mrs Stevens, for their generosity and willingness to see the site become Butterfly Conservation’s second nature reserve in Wales and its first in the north of the country.

The cap of the ridge is ‘limestone pavement’, a distinctive worn and fissured type of dense, hard  limestone that is one of Britain’s rarest habitats. The majority of this habitat in the British Isles is found in the Yorkshire Dales, Cumbria and north Lancashire, where the Carboniferous limestone was scoured by glaciers during the last ice-age. There are only a couple of limestone pavement sites in Wales and this ridge is of particular importance for the extent and quality of the habitat. This importance is demonstrated by the Site of Special Scientific Interest designation that applies to the ridge and adjoining areas of ancient woodland .

View of the Clwydian Hills from the reserve, showing limestone pavement in the foreground.(photo J.Miller)

The pavement’s clints and grikes, formed by post-glacial weathering, make them of great interest as geological features. These fissures, pits and hollows in the rock provide a varied topography and special micro-habitats. This results in a distinctive plant community where limestone calciolous grassland with abundant mosses and lichens, occurs alongside woodland species and those indicative of the acidic soils derived from pockets of decayed vegetation. Hound’s Tongue (Cynoglossum officinale), Mountain melick (Melica nutans) and Moonwort (Botrychium lunaria) are amongst the most notable and distinctive species present. Yellow archangel,(Lamiastrum galeogdolon) Dog’s mercury (Mercurialis perennis) , woodruff (Galium odoratum), wood sorrel (Oxalis acetosella), Harts-tongue fern (Phillitis scolopendria) and Sanicle (Sanicula europara) are normally all indicators of ancient woodland sites and demonstrate how long the clints and grikes have been providing them with moist sheltered conditions.

Natural 'Bonsai' hawthorn tree in the limestone pavement. (Photo J.Miller)	Wall Rue growing in a grike in the limestone pavement       (photo J.Miller)

Another unusual result of the grike habitat, together with years of sheep-grazing in the past, are a collection of naturally-formed "Bonsai" trees – Hawthorn and Ash in particular seem to have clung on to life as short, spreading mats just above the surface of the pavement in some areas. Here the seedling trees must have been growing so far down in the grikes that the sheep were not able to graze them off close enough to the root to kill them.

Pearl-bordered Fritillary (Boloria euphrosyne) (photos R.Whitehead)	Pearl-bordered Fritillary mating pair, showing the underwing with single pearly cell in centre.

The main reason for acquiring the reserve is the importance of the Craig-adwy-wynt ridge for the Pearl-bordered Fritillary (Boloria euphrosyne). This butterfly has declined so much throughout the UK that the population on this ridge is now one of the most important of those known to remain in Wales. Only 17 sites for the species were located in the 1997 UK survey, the species has since disappeared on some of them and Craig-adwy-wynt is one of the few that can be considered a ‘stronghold’. The bare rock and bracken litter with abundant violets make the site’s habitats particularly suitable for this butterfly’s warmth-needing caterpillars. There is a delicate balance needed between the bracken and the violets for the Fritillaries to thrive. The larvae of Pearl-bordered Fritillary usually feeds only on the Common Dog Violet (Viola riviniana), whilst those of the  Small Pearl-bordered (Boloria selene) and Dark Green Fritillary (Argynnis aglaja) generally use a wider selection of violets including Marsh violet (Viola palustris) and Hairy violet (Viola hirta). Research by the Society has shown that the shelter of the growing bracken in April, plus up to 15cms.of the dead plant litter from previous years, raises the temperature around the violets by as much as 15 to 20 degrees above ambient air temperature. The Pearl-bordered Fritillary emerges earlier than most other species from its hibernation as larvae in the litter , so it needs this extra warmth early in the season. The litter provides them with ideal basking surfaces and to a point suppresses most other plant growth apart from violets. However, if the bracken litter gets too deep even the violets can disappear. The presence of suitable nectar sources such as early flowering species like Bugle (Ajuga reptans) and Wood Sage (Teucrium scorodonia) also characterises good Pearl-bordered Fritillary sites. Thus management of such sites is difficult to get right. Experiments are being carried out by volunteers in strimming and then raking bracken litter from controlled patches and monitoring the re-growth of both bracken and violets, plus monitoring their usage by egg-laying female butterflies. This will be a long term project to determine the optimum number of years rotation of such bracken control.

Violets growing again a year after the leaf litter was raked off from under the bracken. (photo J.Miller)

The rapid changes in agriculture and woodland management that occurred during the 20th. century have had a serious impact on this species. Sedentary in its habits, but nevertheless with the capability of colonising over distances of a few miles, it was well adapted to the habitat created by earlier woodland management practices. Its bracken habitat would have been patchy in its suitability, or availability being both controlled and cropped such as for stock bedding. Since WWII the shift to large scale afforestation with conifers, the reduction in regular ride opening and creation of other clearings, and the removal or abandonment of bracken areas, have all taken a toll on the habitat available to this butterfly an others.

But conservation measures to secure a future for this beautiful butterfly in Wales will need more than nature reserves: -their populations need habitat patches to be available in the wider landscape. Butterfly Conservation is already working with Forest Enterprise (an agency of the Forestry Commission)and other local landowners to devise ways of ensuring their woodland management can provide homes for the Pearl-bordered Fritillary. We hope that this reserve will help promote an interest in conservation measures for the butterfly amongst other landowners and managers in the locality.

Other important species also occur on the site. They are not as threatened as the Pearl-bordered Fritillary, but nevertheless are in need of conservation measures. These include Dingy Skipper (Erynnis tages), Grizzled Skipper (Pyrgus malvae), Small Pearl-bordered Fritillary and Brown Argus (Aricia agestis), each of which has quite specialised habitat requirements. With its areas of flowery grassland that warm-up rapidly because of the thin soils, exposed rocks and sheltering scrub, Craig-adwy-wynt provides the sort of specialised habitat that these species, and many others thrive on.

The Grizzled Skipper (Pyrgus malvae), a rare species throughout the UK. (photo; R.Whitehead)

In the absence of grazing, and only slightly checked by rabbits, scrub has taken over in many places at the expense of the more valuable open grassland. However the scrub itself has a variety of tree and shrub species, many of which are also of nature conservation interest: - these include the stunted Wych Elms on which breed White-letter Hairstreaks, the variety of lichens and the important nectar source of the hawthorn flowers. Restoring the reserve’s habitats therefore needs a careful but firm approach to scrub management.

 

Orchids growing across the site include Twayblade (Listera ovata), Butterfly orchid (Platanthera chlorantha) (see photo by R.Miller left) and Early purple (Orchis mascula). There are also some specimens of the rare Welsh Yew; The North Wales Wildlife Trust reserve on the opposite side of the road through Pwll Glas has larger numbers of both the Yew and native orchids.

The Morecombe Bay limestone pavement sites such as Gait Barrows have long been of well known importance for butterflies, with strong populations of High Brown, Pearl-bordered and Small Pearl-bordered Fritillaries. Eyarth Rocks is equally deserving of a high profile for its nature conservation value.

Butterfly Conservation volunteers in North-east Wales as well as from the Wirral and Cheshire, have already put an enormous effort into scrub management on the reserve the last five winters. In their hard work they have had welcome assistance from BTCV volunteers, students from Llandrillo College and professional contractors. The results are excellent and are already benefiting  the site’s butterflies and other wildlife. The maximum count of Pearl-bordered Fritillaries has gone up every year since work began, so that from maximum counts of 4 and 17 in the years immediately prior to BC's acquisition of the site, there have now been maximum counts in the 30s, 50's and of 98 in 2005 and 96 in 2006. The steady increase over these years seems to indicate that our management strategy is working, irrespective of other factors like the weather. 

But more work needs to be done and the aim is to reinstate a suitable grazing regime that will help make the task of controlling scrub growth much easier. For this the site’s boundary walls and fences were repaired in the winter of 2005/06 with the aid of a large grant from EU Objective One funding via CCW, part match-funded by local fund-raising by members of the small North Wales Branch of Butterfly Conservation. A few sheep have now been grazing the site thanks to helpful local farmer, David Baker. Although the main back of the physical work on the reserve has now been broken, more volunteers are always very welcome to help monitor the larval foodplants and classify the many species of mosses, lichens, fungi and other specialists of this unusual habitat. Bracken raking and other occasional physical work may also be needed. Reptile survey traps have recently been placed around the site and there may be a number of other studies that individual volunteers could instigate..

An aberrant form of the Pearl-bordered fritillary, (B.e.ab. albinea) seen in 2001 and 2003 by Rob Whitehead. (photo R. Whitehead)	Local Branch volunteer John Smith dragging gorse off the limestone pavement on one of our regular work parties.   (photo J.Miller)

A bilingual guide leaflet to the reserve is now available; a free printed version from one of the volunteers named below, or click here; Eyarth Guide to view or print out a Pdf version. The leaflet was produced by Alan Wagstaff and Jan Miller and funded by a grant from the Millennium Commission.

To reach the reserve take the Bala road out of Ruthin for about 2 miles. Just before the village sign for Pwll Glas take the left turning signed Llanfair D.C. Immediately over the stone bridge is a layby where there is parking for about 4 cars (do not obstruct the field gate.) Grid Reference; SJ 127553. Follow the public footpath from the corner on the opposite side of this lane, along the old railway line. (Don't confuse this path with the one for the North Wales Wildlife reserve which is on the other side of the main road you have just turned off.) The path is short but quite steep and good walking footwear is recommended. At the stile cross the field along the right side to the stile near the house. Cross the lane and follow the footpath up behind the house. This path goes through woodland and comes out at a gate at the northern end of the reserve.

For further information please contact:

Jan Miller (01352) 711198 e-mail

Rob Whitehead (01824) 704507; e-mail;

Butterfly Conservation Wales office; Swansea: 0870 770 6153 e-mail; wales@butterfly-conservation.org

References;

National Action Plan for Wales (Joy, Bourn et al 1998) Butterfly Conservation.

Species Action Plan for the Pearl-bordered Fritillary, Boloria euphrosyne (Barnett, Warren et al., 1995) Butterfly Conservation.

Records - Rob Whitehead

Eyarth Rocks (SSSI) Site Description , D. Guest, CCW 1997

Full list of butterfly species recorded at Eyarth Rocks;

Common Name                              Latin Name                                  Welsh Name

Pearl-bordered Fritillary                     Boloria euphrosyne                        Britheg Berlog  

Small Pearl-bordered fritillary             Boloria selene                               Britheg Berlog Fach (last record 1998)

Dark-green Fritillary                          Argynnis aglaja                              Britheg Werdd

Grizzled Skipper                              Pyrgus malvae                               Y Gwibiwr Brith  (last record 2000)

Dingy Skipper                                  Erynnis tages                                Y Gwibiwr Llwyd

Large Skipper                                  Ochlodes venata                             Y Gwibiwr Mawr

Small Skipper                                  Thymelicus sylvestris                      Y Gwibiwr fach

Brimstone                                       Gonepteryx rhamni                           Melyn y Rhafnwydd

Brown Argus                                    Aricia agestis                                  Y Gwrmyn Glas

Green Hairstreak                              Callophrys rubi                                Brithribin werdd

White-letter Hairstreak                      Satyrium w-album                            Brithribin wen  

Purple Hairstreak                              Neozephyrus quercus                      Brithribin borffor   

Grayling                                           Hipparchia semele                           Ia^r Fach y Graig (last record 1992)

Holly Blue                                        Celastrina argiolus                           Glesyn yr Eiddew

Common Blue                                  Polyommatus icarus                        Glesyn cyffredin

Speckled Wood                                Parage aegeria                                Brych y coed

Wall Brown                                      Lasiommata megera                         Ia^r Fach y Fagwyr

Gatekeeper                                      Pyronia  tithonus                              Y Porthor

Small Heath                                     Coenonympha pamphilus                  Gweundir Bach

Ringlet                                             Aphantopus hyperantus                    Ia^r  Fach y Glaw

Meadow brown                                  Maniola jurtina                                 Gwrmyn y Ddo^l

Large White                                       Pieris brassicae                              Ia^r Wen Fawr

Small White                                       Pieris rapae                                    Ia^r Wen Fach

Green-veined White                              Pieris napi                                     Ia^r Wen Wythiennog

Orange Tip                                         Anthocharis cardamines                   Boneddiges y Wig

Clouded yellow                                   Colias croceus                                Ia^r Fach Felen

Small Copper                                     Lycaena phlaeas                             Copor bach

Red Admiral                                       Vanessa atalanta                            Y Fantell Goch

Painted Lady                                      Vanessa cardui                               Ia^r Fach Dramor 

Peacock                                             Inachis io                                       Y Peunog        

Small Tortoiseshell                              Aglais urticae                                  Ia^r Amryliw

Comma                                              Polygonia c-album                           Adain Garpiog

There are only two other species regularly recorded in VC 50 and VC 51, and they are Silver-studded Blue and Large Heath. 

 

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