Gough bunting  (Rowettia goughensis)

The Gough bunting is a large, stocky, olive-coloured bunting, endemic to Gough Island in the South Atlantic Ocean. The more or less uniformly olive-green colouration of the adult, which is slightly paler on its underparts, is disrupted only by the yellowish plumage of the forehead and eyebrow, and the prominent black ‘bib' just below the thick-based, pointed black bill. Juveniles, by contrast, possess a buff-olive plumage, heavily streaked above and below with dark brown. The contact call consists of a keet keet sound and the song of a high, twittering whistle (2).

Endemic to Gough Island of the Tristan da Cunha group (St Helena, UK) in the South Atlantic Ocean. The population was estimated at approximately 200 pairs in 1974 and 1,500 in 1991, but recent surveys of breeding territories suggest a population of 400 to 500 pairs (2).

Occurs in all vegetation on the island, but is now most common in the highlands. This distribution may be due to competition with mice in the lowlands (3)

To date, few observations of the breeding behaviour of this species have been made (4). Nests are built on the ground amongst or under vegetation, but mostly on steep slopes or cliffs (2), and clutches usually consisting of two eggs appear to be laid around September and October (4). Adult plumage is not reached for at least three years, but sexual maturity and activity may not necessarily correlate (2). The diet consists primarily of invertebrates (80% of foraging time), but also of fruit, grass seeds, and scavenged birds and broken eggs (2).

This bird's occurrence on only one very small island makes it extremely vulnerable to natural disasters like fires and hurricanes, or to introduced diseases, and especially to the accidental introduction of non-native predators (5). Indeed, the introduced house mouse Mus musculus may pose the greatest present threat through competition and predation (2). Buntings are found at low density in lowland areas where mice are abundant (2), and experiments with ‘dummy' eggs imply that mouse predation on their nests may already be very high (6). Thus, researchers think the bird may have been forced by these mice from the best nesting sites into less suitable upland regions (6). The accidental introduction of the black rat Rattus rattus from Tristan is a huge potential threat, having caused devastation on Tristan to a number of bird species. Worryingly, a dead rat was discovered in a packing case in 1967, another was found on the Gough supply ship in 1974, and there was an unconfirmed rat sighting on the island in 1983 (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. Territory mapping was conducted in 2000/1 to investigate pair densities of Gough buntings in different habitats, in addition to an assessment of the potential role of mice as nest predators. Competition with mice for food and predation by mice has also been scheduled for further investigation during 2003-6 (2). Indeed, the Royal Society for the Protection of Birds (RSPB) has been awarded £60,000 by the UK government's Overseas Territories Environment Programme to fund additional research on the Gough Island mice and how best to deal with them (6). If mice are shown to pose a significant threat, future conservation efforts may focus on their eradication from the island (2). 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 (7).

For further information on the Gough bunting see:

BirdLife International:
http://www.birdlife.org/datazone/species

The Royal Society for the Protection of Birds (RSPB):
http://www.rspb.org.uk

Authenticated (15/05/07) by Ross Wanless and Andrea Angel, Percy Fitzpatrick Institute of African Ornithology. 
http://www.fitzpatrick.uct.ac.za