The invasive House Mouse Mus musculus is a key factor in the highly threatened status of three species that breed predominantly on Gough Island. Predation by this introduced species is contributing to continued long-term population declines in Atlantic Petrel Pterodroma incerta, Tristan Albatross Diomedea dabbenena and Gough Bunting Rowettia goughensis.
The introduced House Mouse Mus musculus is devastating seabird populations on remote Gough Island, the most southerly of the Tristan da Cunha group (St Helena, to UK) in the Southern Atlantic. There are 22 bird species nesting on Gough, of which 20 are seabirds. Among the affected species are the Critically Endangered Tristan Albatross Diomedea dabbenena and the Endangered Atlantic Petrel Pterodroma incerta, which breed predominantly on the island (9,000–15,000 individuals and c.1.8 million pairs respectively).
It is estimated that c.60% of all chicks die before fledging each year owing to mice predation (Cuthbert and Hilton 2004, Cuthbert et al. 2004, Wanless et al. 2007), amounting to an estimated half a million chicks during the last breeding season (RSPB 2008). For Atlantic Petrel, population models suggest that this predation is contributing to a population decline of 1.7–3.6% per annum (Cuthbert 2004). For Tristan Albatross, recent counts indicate that the population on Gough has decreased by 28% over 46 years, with population models predicting annual decline rates of 2.8% (as a result of mouse predation of chicks and bycatch of adult and immature birds in fisheries; Wanless et al. 2009). In 2008, Tristan Albatross suffered its worst breeding season on record and productivity is estimated at five times lower than it should be (RSPB 2008). These data suggest a decline equivalent to >79% over 70 years (three generations) from 1955 to 2025, hence this species’s categorisation as Critically Endangered in the 2008 IUCN Red List.
Predation of eggs and chicks by mice, in combination with competition for food, is also devastating the population of an endemic landbird, the Gough Bunting Rowettia goughensis. This species has also been uplisted to Critically Endangered owing to alarming declines that have reduced the population to just 400–500 pairs (RSPB 2008). The House Mouse is one of 2,900 non-native species damaging native wildlife on the 17 UK Overseas Territories and Crown Dependencies (Varnham 2006).
Related Case Studies in other sections
BirdLife International (2008) Native birds on Gough Island are being devastated by house mice. Presented as part of the BirdLife State of the world's birds website. Available from: http://www.birdlife.org/datazone/sowb/casestudy/175. Checked: 30/08/2015
|Key message: Invasive species are a particular threat on islands|