mew island
Mew Island from Lighthouse Island Photo: Tessa Coledale

This week we’re going to focus in on the two Outer Copeland Islands, Mew Island and Lighthouse Island. The Copeland Island group consists of three islands in the North Irish Sea off the coast of a wonderfully named town called Donaghadee. The two outer isles will be covered by one biosecurity plan as they are only separated by 50m of open water at low tide so invasive predators reaching one island are very capable of spreading to the other island. Big Island is approximately 1.3km inland from these outer isles so will be dealt with separately.

ManxShearwater RSPBimages ChrisGomersall

Manx Shearwater Photo: Chris Gomersall (rspb-images)

All three islands were designated as a SPA for holding 1.7% of the world’s population of breeding Manx Shearwater and 22.6% of the Irish population of breeding Arctic tern. These burrow nesting and ground nesting seabirds are particularly susceptible to predation by invasive mammalian predators compared with cliff nesting seabirds that often remain inaccessible to invasive species.

Mew Island is owned by Irish Lights and hosts a 37m tall lighthouse, built in 1884. This was manned until 1996 but now the island is uninhabited with no public access. Back in 1941 there were an astonishing 12,400 terns on Mew island including over 200 pairs of Europe’s rarest seabird the Roseate tern. By the mid 1960’s there were no terns breeding on Mew Island but breeding attempts have started to increase in recent years thanks to concerted conservation efforts. The Copeland Bird Observatory (CBO) have an agreement with Irish Lights that allows them to visit the island to monitor bird populations particularly the nationally important numbers of breeding Eider duck.

Mew Island lighthouse

Mew Island lighthouse Photo: Tessa Coledale

CBO has been in existence since 1954 and manages Lighthouse Island on a long-term lease from the National Trust. The original lighthouse established in the early 18th century was found on Lighthouse Island; the tower has since been removed though so the name often confuses people!

CBO is operated on a part time basis by local voluntary ornithologists who carry out bird ringing under the auspices of the British Trust for Ornithology ringing scheme. CBO is a member of the Bird Observatories Council and collects data on breeding and migratory birds as well as managing Lighthouse Island habitat for the benefit of birds. They already have wax chew blocks in wire cages distributed in suitable locations around the island following a possible rat sighting back in 2017. Thankfully no further evidence of rats was found but volunteers remain vigilant when visiting the island in order to protect almost 3000 pairs of Manx Shearwater that breed underground in burrows on the island. It was great to see biosecurity information and a biosecurity log filled in by volunteers on each of their round island checks during a recent visit to Lighthouse Island.

Big Island and the mainland from old lighthouse on Lighthouse Island

Looking across to Big Island and Northern Ireland mainland from old lighthouse on Lighthouse Island Photo: Tessa Coledale

We are working with Irish Lights, National Trust and Copeland Bird Observatory to help finalise a biosecurity plan for the outer isles. Following that we’ll look at helping them install biosecurity measures on Mew Island and increasing the attractiveness and longevity of the wax chew blocks on Lighthouse Island by placing them in covered stations which rodents are more attracted to because they can hide or nest in them. Once the chew blocks are placed inside, they’ll be protected from the weather but it’s still important to replace them every few months to maintain the attraction to rodents. The old wax can just be melted down and re-used with additional flavouring, so the wax blocks themselves are a very cost-effective way of detecting invasive rodents.

Open biosecurity surveillance station showing fresh wax block  Tom Churchyard

Open biosecurity surveillance station Photo: Tom Churchyard

There are no unauthorised landings on Lighthouse Island, although you can arrange to visit through CBO


Remember to Rat on a Rat Photo: Tessa Coledale



April 2020

Skokholm, Skomer and Middleholm

Together these islands are estimated to hold a remarkable 67% of the world population of breeding Manx shearwater. These birds are diurnal but will only come ashore or go out to sea under the cover of darkness and nest underground so you’re unlikely to see them when you visit the islands unless you stay overnight. You will see that the ground is covered in burrows and is therefore extremely fragile so take care to stay on the paths when you visit. Skokholm is also home to the fourth largest storm petrel colony in the UK, holding 8% of the UK breeding population. These birds’ nest in crevices in stone walls or quarries and are also nocturnal when on land to avoid predation. The islands most famous resident however is the puffin, these birds nest underground but come out in the day so you are likely to see rather a lot of them if you visit between April and July. All these ground-nesting species are particularly susceptible to invasive non-native mammalian predators, they would not survive if rats, mink or stoats arrived on the islands.

March 2020


Grassholm is one of those islands that assaults your senses upon approach with both the smell, noise and sight of over 36,000 pairs of gannets. On a round island boat trip you’ll see them on their nests or flying overhead like aeroplanes before folding their wings back and diving at speed to catch their prey in the surrounding waters. 6.8% of the world population of Northern gannets breed on this lump of rock just 10 hectares in size. In fact, the majority of the island is now white in colour due to the animals and their guano, with only a relatively small strip of grass remaining where they are yet to colonise. Grassholm is the third largest gannetry in the UK after the Bass Rock and St Kilda – two other sites we’re also working on.

March 2020

The Farne Islands

Lying only a mile off the Northumberland Coast, the Farne Islands archipelago hosts one of England’s most impressive seabird colonies, managed by the National Trust. Depending of the state of the tide, the Farnes boast between 15 and 28 islands, the largest being just 16 acres in size. Onto these small isles, an assemblage of over 160,000 seabirds crowd together each summer to breed.

Illustration of birds

Contact Us

If you’d like more information or would like to report a sighting of an invasive predator please contact us using the form below: