A suspicious gnaw mark, a specialist detection dog and new island surveillance - it's been a busy year for the team protecting Wales' seabird islands from invasive predators.
5 min read
Biosecurity for Wales work with 13 islands around the coast of Wales designated as Special Protection Areas (SPAs) or Sites of Special Scientific Interest (SSSIs) for breeding seabirds. Welsh islands are globally important for breeding seabirds, including over half the world’s population of Manx Shearwater, the third largest Gannetry in the world and significant numbers of many other species.
Our focus is simple: prevent invasive mammalian predators, such as rats, reaching the islands; detect any incursions quickly; and respond immediately to prevent predators breeding and destroying seabird populations by eating eggs, chicks and even adult birds. One pregnant rat can produce a colony of more than 300 in just eight months, so rapid response is crucial.
On the 20 of April, gnaw marks were discovered on a wax chew block during routine surveillance on the Skerries, a group of rocky islets 3km off the northwest corner of Anglesey designated as an SSSI for breeding terns, including Arctic, Common and Roseate, as well as Puffins. Thanks to the Skerries Biosecurity Plan, developed jointly by the island manager and the biosecurity team, staff were able to quickly put a response into action, securing the necessary permit to use rodenticide, collecting equipment from our Rapid Response Hub, and setting up a rodenticide grid across the island. At the same time, our Conservation Detection Dog team, Greg and Jinx, searched the island for signs of rats.
Fortunately, no further signs were found, suggesting the gnaw marks were most likely made by a single rodent, which appears to have died during the harsh winter. It was a lucky outcome, but also a sobering reminder of the importance of staying vigilant.
Traditional methods of surveillance such as camera traps and wax chew blocks are deployed across islands year-round to alert us early to an arrival of rats. But, we also have Jinx and his handler Greg. Jinx is a detection dog, trained exactly as bomb and drug detection dogs but on the scent of rats. We aim to get Jinx over to each island at least once a year to actively search for rats, but unsettled spring weather made island visits difficult this year. Despite this, Greg and Jinx completed routine checks of Skokholm and Ramsey, while the Biosecurity for Scotland dog team, based temporarily in North Wales, checked Bardsey. Their support freed up Greg and Jinx to concentrate on boat and cargo checks – another vital part of preventing rodents reaching the islands.
Years of planning and several failed attempts paid off when we finally reached Cardigan Island to deploy surveillance equipment with the islands’ manager from the Wildlife Trust of South and West Wales. The aim is to confirm the island remains rodent-free and use the findings to update the Biosecurity Plan.
Away from the islands, we've been raising awareness before visitors set sail. New biosecurity signage has been installed at Martin's Haven, where boats leave for Skomer, following rat sightings around the jetty. Biosecurity for Wales beer mats and leaflets are being distributed through local businesses, providing biosecurity checklists and practical advice to help visitors protect Wales' internationally important seabirds.
We’ve recently put more surveillance equipment directly into the hands of island staff and communities to ensure that rodents are detected quickly. These new "'mini hubs’ include both standard and remote camera traps, plus identification guides to help teams confidently identify gnaw marks and footprints. Additional support, training and equipment have also been provided following unusual predation events on Bardsey and Flat holm.
Trinity House, the general lighthouse authority for Wales, England, the Channel Islands and Gibraltar regularly visit islands to maintain their lighthouses. With lighthouses on seven of our thirteen seabird islands in Wales, we have helped develop a new Biosecurity Plan for Trinity House staff, implementing biosecurity methods and raising awareness of the dangers of introducing new species to these islands.
From responding to suspicious gnaw marks on the Skerries within days, to finally reaching Cardigan Island, 2026 has repeatedly highlighted the importance of island biosecurity, keeping these islands and the seabirds that depend on them safe from rats.
