Gough Island is home to four seabird species found only within the Tristan da Cunha island group, and two endemic land birds. Gough has been described as the greatest seabird island in the South Atlantic, and as one of the most important seabird breeding grounds in the world. But many birds which nest here have been under threat, including two Critically Endangered British birds: the Tristan albatross and Gough bunting. 

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Mouse predation was directly impacting many species, each year pushing them closer to extinction. Now we have completed the eradication attempt we hope these birds can enter this next breeding season on a mouse-free island. 

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Between now and 2024 we will be looking out for any sign of mice on the island. In 2024 we hope to return to Gough to conduct an intensive search for mice. If we fail to find any mice in 2024 we will be confident we have succeeded in our endeavour to eradicate them. Between now and then, we expect to see significantly increased breeding success rates across many species. However, this in itself does not mean we have eradicated the mice as if only a few mice remain we would expect their impact on birds to be minimal until the mouse population rebounds. However, increased breeding success rates will give an indication of the likely recovery of species should we be able to go on to confirm eradication success.

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Tristan albatross – Critically Endangered

These magnificent seabirds breed on Gough Island and mate for life. Sadly, there are only around 5,000 mature individuals in the world - and almost all of them breed on Gough (no more than 3 pairs are thought to breed anywhere else). Due to mouse predation on Gough, only about a third of the island's breeding pairs managed to raise a chick - which is a very low proportion compared to other large albatrosses. In 2021 a an adult albatross was killed by mice. Without intervention, the Critically Endangered Tristan albatross might have gone extinct. 

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Gough bunting – Critically Endangered

This charming songbird is known only from Gough Island. Historic population declines are likely due to mouse predation and the species is now confined to sub-optimal habitat on Gough where there were fewer mice.

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Atlantic petrel – Endangered

This cryptic bird is almost completely reliant on Gough Island to breed, with over 99% of the entire global population found here. Atlantic petrels were particularly hard-hit by mice predation – with as few as 12% of eggs surviving to fledge each year. In their first breeding season since the mouse eradication attempt, we believe their breeding success to be around 63%!

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With no action, the Atlantic petrel would have been lost from Gough Island, forever. This would have left a global population of around 50 breeding pairs which would have placed the species in critical danger of extinction.

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MacGillivray’s prion - Endangered

The MacGillivray’s prion was only discovered on Gough in 2013, having previously been assumed to be a similar species with a broader bill (the broad-billed prion) which breeds in large numbers on the island. The MacGillivray's prion is also found in very small numbers in the Indian Ocean, where they have already been lost from a major breeding island (Amsterdam Island) due to the impact of invasive predators. Therefore, the vast majority of its world population now breeds on Gough.

 

The MacGillivray's prion, although far more abundant on Gough than albatrosses, was also threatened with local extinction due to the impacts of mice. Over the past 70 years the breeding population on Gough has lost more than 1 million pairs. In our monitoring colony, breeding success in recent years has regularly been as low as 0%, with no chicks surviving to fledge. The MacGillivray's prion and similar small, highly threatened petrel species were therefore in critical need of intervention. Without the eradication of mice these species will continue to decline until they are lost from Gough Island forever.

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Given that we know that the MacGillivray's prion has already been lost once from a major breeding island due to predation by invasive non-native species, we hope we have been successful in our mission to eradicate the mice from Gough so as to prevent a similar loss here.

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