At a glance
Ancient alkaline fen NNR in central-east Anglesey — 14 orchid species including the rare fen orchid, 20+ dragonfly/damselfly species, water voles, and nationally important wetland flora. Boardwalk paths into the fen. Free; NRW managed. Peak season June–August (orchids then dragonflies). No facilities. Limited roadside parking. 4 miles from Llangefni. LL76 8TH.
About Cors Goch
Cors Goch ("Red Bog") is one of the finest surviving alkaline fen habitats in Wales — a National Nature Reserve managed by Natural Resources Wales in the interior of Anglesey, where calcareous groundwater flows through ancient peat to create conditions supporting a richness of species found almost nowhere else in north Wales. Unlike the acidic upland bogs common in Snowdonia, alkaline fens are lime-rich and support distinctly different communities: in Cors Goch's case, 14 orchid species (including the rare fen orchid, protected under European habitats legislation), over 20 species of dragonfly and damselfly, water voles, and a diversity of wetland plants that reflects centuries of careful, low-intensity management.
Boardwalk paths allow access into the fen without the need for wellington boots — though the paths can be narrow and slightly uneven in places. The peak season runs from June (first orchids and dragonflies) through August (peak dragonfly activity). Dawn and dusk visits on warm summer days give the best chances of seeing both water voles and the more spectacular hawker dragonflies patrolling the open water.
Free entry. No facilities on site. Limited roadside parking. Combine with Cors Bodeilio (5 miles) for a day focused on Anglesey's exceptional fen habitats, and Oriel Môn in Llangefni for the island's best museum.
Find it on the map
Frequently asked questions
Cors Goch ("Red Bog" in Welsh) is an ancient alkaline fen — a type of wetland habitat formed where calcareous (lime-rich) groundwater flows through peat, creating conditions that support a different and often richer flora than the more acidic bog habitats common in upland Wales. Alkaline fens are rare in Britain and have declined dramatically through drainage and agricultural improvement; Cors Goch is one of the best remaining examples in Wales. The lime-rich water and the diversity of microhabitats within the fen (open water, reed swamp, sedge fen, rush pasture, carr woodland) support a remarkable range of species. The reserve has been identified as a Site of Special Scientific Interest (SSSI) and designated as a National Nature Reserve because of its outstanding botanical and entomological interest. The combination of 14 orchid species, 20+ dragonfly and damselfly species, and rare plants including fen orchid is essentially unmatched in north Wales.
Cors Goch supports 14 species of orchid — an exceptionally high count for a Welsh site and reflecting the diversity of habitats within and around the fen. The most significant is the fen orchid (Liparis loeselii), one of Britain's rarest plants, found at only a handful of sites in Wales and protected under European habitats legislation. The fen orchid is inconspicuous (small, yellow-green flowers) but its presence indicates the pristine condition of the fen habitat. Other orchids include southern marsh orchid (the most abundant, forming impressive stands in June–July), early marsh orchid, common spotted orchid, bee orchid, pyramidal orchid, green-winged orchid, fragrant orchid, greater butterfly orchid, and several hybrid orchids. The orchid season runs from approximately late May (early marsh orchid) through to August (common spotted orchid), with peak diversity in June and early July.
Cors Goch's combination of open water, reed beds, and wet grassland supports over 20 species of Odonata (dragonflies and damselflies) — a very high count for a site of its size. Common species include the emperor dragonfly (Britain's largest dragonfly, vivid blue in the male), four-spotted chaser, brown hawker, common hawker, and several darter species (common darter, ruddy darter, and sometimes black darter). Damselflies are often more numerous than dragonflies: azure damselfly, common blue damselfly, large red damselfly, and blue-tailed damselfly are all common. The rare variable damselfly (Coenagrion pulchellum) has been recorded at Cors Goch. The peak season for dragonfly and damselfly watching is July and August; on warm sunny days the flight of hawker dragonflies over the open water and the perching of darters on prominent plant stems make for outstanding wildlife watching.
Yes — water voles (Arvicola amphibius) are present at Cors Goch, though as with all British water vole populations they are elusive. Water voles are Britain's fastest-declining native mammal: once common along waterways and in fen habitats throughout Britain, they have been almost eliminated in many areas by the introduced American mink, which hunts them in their burrows. Anglesey has a mink control programme (managed by the Anglesey Mink Project) which, combined with Cors Goch's isolated and well-managed fen habitat, gives the water vole population here a better chance than in many mainland sites. The best way to detect water voles is by looking for their feeding stations (piles of neatly cut vegetation stems with 45-degree cuts) along the fen edges, and by listening for the distinctive "plop" as they enter the water when disturbed. Dawn and dusk in summer are the best times for water vole sightings.
Cors Goch and Cors Bodeilio are both ancient alkaline fen NNRs on Anglesey and are ecologically similar — reflecting the unusually high concentration of this rare habitat on the island. Cors Goch is generally considered the more accessible and slightly larger of the two sites, with boardwalk paths that allow visitors to enter the fen without getting wet feet. Cors Bodeilio (near Llangefni, 5 miles south-west) has a similar orchid and dragonfly interest but is slightly less visited and has a higher proportion of carr woodland (wet scrub dominated by willow and alder) in its current condition. Both sites are excellent and complementary — a day visiting both, combined with a stop at Oriel Môn in Llangefni (the best museum on Anglesey), gives an excellent introduction to the natural and cultural heritage of the island's interior away from the coast.