Terns from abandoned Skerries colony found at multiple Irish Sea sites
The Skerries, which hosts the UK’s largest colony of Arctic terns, was abandoned this year due to disturbance.
However, some of these birds have been recorded nesting at other tern colonies across Wales, England, and Ireland confirming the importance of having alternative safe nesting sites.
The Skerries, which are a group of rocky islets off the coast of Anglesey, north Wales supports a variety of nesting seabirds, such as puffins, herring gulls, common terns and in recent years roseate terns. It is also home to the UK's largest colony of Arctic terns with 2,814 breeding pairs recorded in 2019.
The islets are owned by Trinity House and during the summer, RSPB Cymru wardens live in the lighthouse to protect and monitor the seabird assemblage. The existence of an EU funded LIFE Project has helped improve their infrastructure and extend the wardening period. In light of the Covid-19 pandemic, wardening was not feasible this year, and in the absence of a human presence on the island, an immature peregrine falcon took up residence on the islands, causing the tern colony to abandon the site. Usually, people’s presence on the island would have deterred peregrines from roosting on the islands – something the terns won’t tolerate.
Luckily, British Trust for Ornithology (BTO) licensed ringers have been annually colour-marking a small percentage of the nesting terns as part of a Retrapping Adults for Survival (RAS) project. This involves fitting the bird with a unique code which allows the members of the public to report their locations and help further understand the terns’ movements after leaving the Skerries.
Nearby Cemlyn Lagoon Nature Reserve, managed by the North Wales Wildlife Trust, and another Welsh site saw increases of up to 1,000 breeding pairs of terns between them, and as a result of the RAS project it has been possible to prove that some of these birds had come from The Skerries. In addition we have learned that a common tern from the Skerries has been breeding at RSPB Hodbarrow in England as has an Arctic tern has been seen at Dalkey Island (managed by BirdWatch Ireland and Dún Laoghaire-Rathdown County Council) in Ireland.
These figures and re-sightings of marked birds prove that the nesting terns within the Irish Sea are part of one big metapopulation and that international collaboration is essential if we want these species to thrive. Common and Arctic terns face many pressures and threats, however with conservation organisations protecting tern sites within this area, should a colony collapse, then the terns have alternative safe nesting areas to choose from.
RSPB Cymru North Wales Wetlands Warden, Ian Sims, said:
‘It was devastating to see the desertion of the Skerries this year, so it’s really heartening to know that a large proportion of the terns have been able to use the network of well-managed colonies around the Irish Sea to give themselves a second chance of raising young this season.’
7 September 2020
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