We are celebrating the recovery of the Manx shearwater on Lundy Island. Owned by the National Trust and leased to the Landmark Trust, Lundy has always been famous for its seabirds. Lundy, in Norse, means Puffin Island and there are puffins there today. But the real gem is the Manx shearwater. Most of these birds (over 90 %) breed on islands off the British and Irish coasts. Until a decade ago it was doing badly, almost certainly because of predation by rats. With just a few hundred pairs left on the island and their eggs and chicks eaten by rats, there was real prospect of losing them completely, as happened on the island of Canna (Inner Hebrides).
Back in 2002, the Seabird Recovery Project partnership of National Trust, RSPB, English Nature (now Natural England) and Landmark Trust was formed to try to save Manx shearwaters on Lundy. Our priority, removing the brown rats (common) and black rats (ship). Globally both are widespread and abundant. In Britain and Ireland the black rat is only found on a few islands and dockland warehouses – it is really rare. How could we remove one of Britain’s rarest mammals from one of its few refuges? Our priority – indeed our global responsibility – was to rescue the dwindling population of Manx shearwaters on Lundy.
By 2013, nearly a decade after rat removal, there are now thousands of shearwaters breeding on Lundy, and their burrows are in many more parts of the island than when the rats were present. The speed of recovery has been remarkable. Manx shearwaters spend the first five or six years of life at sea, in the south Atlantic. The contribution of these home-bred birds to the increase must have been small - it must have involved birds from other colonies. I reckon that shearwaters from the massive colony on the islands off Pembrokeshire have always visited Lundy, and they may have tried to breed. But until the rats went they were always deterred or their eggs and chicks were eaten.
Removing rats from islands with shearwater colonies does not always result in a quick recovery of the shearwaters. It did on Ramsey off Pembrokeshire, but it has not happened on Canna where rats were also removed about a decade ago. This is curious. Canna is next door to the huge shearwater colony on the island of Rum. Does Rum have enough birds to export to, and recolonise, Canna? We have high hopes rats will be removed from the Calf of Man (where there really should be lots of Manx shearwaters), and also on Scilly, to allow the recovery of this amazing bird. My hunch is that if and when the rats are removed from the Calf, the shearwater population will recover quickly. We already know that Welsh island birds spend the later part of the summer in the northern half of the Irish Sea, so are in the area for some of the year. But where would immigrant shearwaters to recolonise Scilly come from? Recovery there may take some time. In the meantime, on islands where rats have been removed you seem to get a recovery of ground-nesting and other birds and large insects such as big beetles, so rat eradication from seabird island – however unpleasant – is an ecological win win.
Stop press – Great to see that the puffins on the National Trust’s Farne Islands have recovered from their low count in 2008. A stonking 40,000 pairs!
- Dr David Bullock- Head of Nature Conservation at the National Trust