Atlantic petrel  (Pterodroma incerta)

Although still common, the Atlantic petrel qualifies as Endangered because it has a very small breeding range, with the vast majority of the population on just one island (2). Such a limited range places the bird at risk from chance events such as natural disasters or the introduction of mammalian predators (2) (6). On Gough, the only introduced predator is the house mouse (Mus musculus), with mouse predation thought to be responsible for a significant proportion of the 700,000 Atlantic petrel chicks (about 60 percent of the island's population) that are reported to have died before fledging in 2000 and 2001 (7). The large population of native southern skua (Catharacta antarctica) are also known to feed on seabirds including the Atlantic petrel (2). One reason for the bird's near extinction on Tristan Island, where it was once common, is that it was formerly one of the few sources of food for the islanders during winter (6). However, the bird is now scarce on the island and is very unlikely to be exploited today (2). On Tristan, rats are also thought likely to have affected breeding success (2).

A cat eradication programme on Tristan in the 1970s was highly successful, eliminating this potential predator and helping to protect the island's endangered native birds (2). Fortunately, Gough Island is well protected, with the island being a nature reserve and World Heritage Site, uninhabited apart from the staff that run a meteorological station (2). In 2000/1 the first ever quantitative population survey was undertaken on Gough, coupled with research into breeding ecology and reproductive output of this species (2). Further research on reproductive success and mouse predation was begun in 2003 (2). The Gough mice are known to be endangering a number of threatened bird species on the island, and further research into this issue is a high priority. If mice are shown to pose a significant threat, future conservation efforts may focus on their eradication from the island. Gough Island is widely recognised as having one of the most diverse bird colonies in the world, including four endangered species, and every effort continues to be made to protect it and the rich biodiversity it hosts (8).