YNYS MON TY CROES National Grid Reference: SH328692

Site Area: 28.1 ha


Ty Croes is of special interest for its coastal heathland, grassland and associated rock and flush habitats and also the marsh fritillary butterfly.

The site is located on the rocky coast at the former military base of Ty Croes, west of Aberffraw. The underlying bedrock, which outcrops on the shoreline, is Precambrian mica schist of the Mona complex. The terrain rises as low rocky cliffs from the shore through the convex slope of the heath to a maximum height of approximately 35m. The soils over most of the site are shallow, sandy podsolic rankers over bedrock which, with the exposure of the site to westerly gales and salt spray, account for the low and nutrient-poor nature of the vegetation. A number of small seepages drain the site.

The site is of special interest for its vegetation which comprises a mosaic of coastal heathland, grassland flushes and cliff communities. The heathland is characterised by the cross-leaved heath Erica tetralix, heather Calluna vulgaris, spring squill Scilla verna, western gorse Ulex gallii and heath grass Danthonia decumbens. To seaward, maritime grassland of red fescue Festuca rubra, thrift Armeria maritima and plantain Plantago spp. is found. In crevices on the cliffs are patches of rock samphire Crithmum maritimum, and rock sea-spurrey Spergularia rupicola. This sequence of communities, related to the wind and salt exposure and soil thickness, is dissected by a series of wet flushes.

The heath is notable for the abundance of petty whin Genista anglica and allseed Radiola linoides. The nationally uncommon golden-samphire Inula crithmoides occurs on these cliffs. A number of small flushes drain the area and here species such as common yellow sedge Carex veridula subsp. oedocarpa, saltmarsh rush Juncus gerardii, marsh arrowgrass Triglochin palustris, brookweed Samolus valerandi and yellow iris Iris pseudacorus are found.

Chough Pyrrhocorax pyrrhocorax, which nest nearby, feed on invertebrates found in the soil and short vegetation. Marsh fritillary Eurodryas aurinia is found on the site where it is dependent on its food plant, devil's-bit scabious Sucissa pratensis, in the wetter areas.


The marsh fritillary butterfly is protected under the Wildlife & Countryside Act 1981 (Schedule 5) and the chough is protected under the Wildlife & Countryside Act 1981 (Schedule 1).