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Ramsey Island, 259 ha, is ca. 1 km off the Pembrokeshire coast, south-west Wales. The eradication of brown rats (Rattus norvegicus) was successfully completed in the winter 1999/2000 using a ground-based bait station operation. The pre-eradication survey using tape playback estimated the Manx shearwater (Puffinus puffinus) population to be 849 pairs. These surveys were repeated in 2007, 2012 and 2016. Each survey showed the Manx shearwater population had increased, reaching 4,796 pairs in 2016 with birds spreading from previously known breeding locations. European storm petrels (Hydrobates pelagicus) were ?rst recorded breeding on Ramsey Island in 2008 with up to 12 pairs in 2016 (a minimum estimate based on accessible survey areas). Other species have also shown improvements to population estimates and range since the rat eradication. This evidence shows that there can be little doubt that the presence of brown rats on Ramsey played a signi?cant role in suppressing breeding numbers and limiting the breeding range of seabirds on the island and the positive results following the successful eradication are now being seen.

Eradication techniques using ground-based devices were developed in New Zealand in the early 1970s to target invasive rodents. Since then, different bait station designs, monitoring tools and rodenticide baits have been developed, and changes in field techniques have improved and streamlined these operations. The use of these techniques has been taken around the world to eradicate rodents from islands. Eradication technology has moved rapidly from ground-based bait station operations to aerial application of rodenticides. However, regulations, presence of and attitudes of island-communities and presence of a variety of non-target species precludes the aerial application of rodenticides on islands in many countries. As such, ground-based operations are the only option available to many agencies for the eradication of invasive rodents from islands. It is important to recognise that the use of ground-based operations should be a valid option during the assessment phase of any eradication proposal even in countries that can legally apply bait from the air; in many instances the use of ground-based techniques can be as economic and rapid. The use of ground-based operations can also facilitate opportunities for in-depth monitoring of both target and non-target species. Using examples of the techniques and developments used in five ground-based rat eradication operations from the UK demonstrates how these methods can be used safely and successfully around the world, even on islands in the order of hundreds of hectares and those with communities.

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