Contemplating Cemlyn

Contemplating Cemlyn

Cemlyn Nature Reserve_Lin Cummins

The fragility and tenuous chain of events that have allowed Cemlyn to be the only breeding Sandwich tern colony in Wales is an amazing story.


The fragility and tenuous chain of events that have allowed Cemlyn to be the only breeding Sandwich tern colony in Wales is an amazing story. It’s a combined story of nature and the influence of man. It has only survived due to the management of the site by North Wales Wildlife Trust and it is so very important – it has recently held about 3% of the world Sandwich tern breeding population and 20% of the UK population.

When you look at the tern island and the Cemlyn ridge from the nearby hill or rise in the road you appreciate how fragile the whole area is to sea level rise. NWWT can manage water levels to some extent with the weir on the west side of the lagoon. But serious storms combined with high tides and the threat of rising sea levels adds to the overall vulnerability of the site.

There are so many threats to the short-term and long-term survival of the tern colony – some of which are under our control and others not so. In ‘normal’ circumstances managing visitors and preventing disturbance to the nesting terns is a key part of the job of summer wardening of the site. We are still doing that this year in case somebody comes and does something untoward. Even letting a dog loose on the ridge when the colony is nesting can have devastating consequences.

Natural predators and the disturbance they can cause are also a serious threat; from otters to geese and the larger gulls and birds of prey. This is something the Trust has generally managed well over the years, successfully minimising the impact while allowing the species to co-exist..

And there are other potential issues as well; the exploitation of the marine environment continues to affect many seabirds and marine wildlife. Should Wylfa Newydd ever get the go ahead this could also potentially severely impact the lagoon and tern colony. The Wildlife Trust, alongside the National Trust and RSPB, have worked hard over several years to make the case for Cemlyn and its terns and other wildlife. We await the planning decision- now expected in September 2020.

Wild Intelligence

The breeding season is well under way and we all hope for a good success rate. I sit watching the islands from across the lagoon and the large patches where the Sandwich terns have settled are shining brilliant white in the sunshine. The rest of the islands are scattered with the characterful raucous Black headed gulls which play an important part in sheltering the Sandwich terns from predation while nesting. 

I love the way the Sandwich terns are often described as being ‘highly strung’. They are nervy and ‘flighty’ especially early in the breeding season – so easily taking fright and flying up in the air simultaneously aptly called ‘a dread’. They look so pristine and smart and sophisticated compared to the medley of black headed gulls. The Sandwich terns’ spiky black heads and the way they dance like tribal Africans – circling each other in their fascinating courtship dances are uniquely beautiful. Indeed, with their long flight from Africa to breed right here at Cemlyn – each bird truly is a miracle of toughness and wild intelligence.

 Each bird looks robust yet their survival into the future is as tenuous as their past.

Cemlyn NWWT Nature Reserve at High Tide

The curve of Esgair Cemlyn highlighted by high tide © Caroline Bateson

Local and Special

Whilst our nature reserves remain open for local people, please only visit if guidelines from Welsh Government permit you to do so, and follow all appropriate social distancing measures.

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