Lundy, Seabirds and Rats - Killing in the name of conservation

Lundy is a rugged island located in the mouth of the Bristol Channel, its western flanks facing the full force of the Atlantic. Owned by the National Trust and leased to, and managed by, the Landmark Trust, Lundy was traditionally feted among ornithologists for its seabirds. By the end of the 20th Century its star was waning, in part due Man’s exploitation of the marine environment, but also because of the impact that predatory rats - introduced and alien to Lundy - were having on breeding birds.

Manx Shearwaters spend their UK days at sea and only return to land under cover of darkness. At dusk, birds can be seen gathering in large ‘rafts’ off Lundy’s west coast. ©Paul Sterry/Nature Photographers Ltd.

In 2002 a project began to eradicate the island’s Brown and Black rats, the work undertaken by a team from New Zealand. The project involved the collaboration of RSPB, Natural England, the Landmark Trust and the National Trust and was a success, with Lundy being declared ‘rat free’ after four years. Since then bird numbers have risen steadily: in 2019 the RSPB said the population of seabirds on Lundy had tripled to 21,000 birds.

Lundy’s Puffins have also been winners in the rat-eradication stakes with a breeding population that is rising steadily year by year from just 13 birds before rodent eradication to 375 in 2019. ©Paul Sterry/Nature Photographers Ltd.

Of particular interest are Manx Shearwaters whose Lundy population has grown from 297 pairs (prior to rat-eradication) to 5,504 pairs in 2019. Something like 80% of the world population breeds in the UK giving us a global responsibility. Of these the vast majority breed in just a few locations: 40% on the Scottish island of Rum, and 50% on Pembrokeshire islands including Skomer and Skokholm. This breeding concentration makes them vulnerable to local extinctions, and highlights the need to establish new colonies and reinvigorate ones like Lundy that without human intervention would most likely have faded into oblivion.

Lundy Wheatears often nest among the Thrift, sometimes using abandoned Rabbit burrows. No longer troubled by predatory rats, they are thriving. ©Paul Sterry/Nature Photographers Ltd.

Interestingly, it is not just the seabirds that have benefitted from the eradication of rats. A predictable consequence has been a dramatic increase in numbers of ground-nesting birds such as Wheatears and Skylarks. A perhaps unforeseen consequence has been a noticeable improvement in the quality of native vegetation and habitats, most significantly the ‘waved’ maritime heath that tops the island away from land which is ‘farmed’.

Andrew Cleave MBE.