remains a potential threat, the impact of which has not been fully assessed1. Grazing pressure from sheep is leading to habitat degradation on La Gomera and at El Hierro. Forest fires also pose a moderate threat to its habitat. Recreational activities cause some disturbance in the breeding season. The species is potentially threatened by outbreaks of Newcastle Disease and Tuberculosis. The natural habitat is tall laurisilva forest or dense tree heaths which are cloud-covered for much of the year. The forests consist mainly of Azores Laurel, Oreodaphne foetens, Til, Madeira Mahogany, Canary Laurel, Faya, Lily of the Valley Tree and the Picconia. The Trocaz pigeon prefers primary forests, but secondary growth is used for feeding, and agricultural land is also visited, especially at times of fruit shortage. Most of the pigeons are found below 1000 m (3300 ft), and their prime environment appears to be steep ravine-indented slopes along artificial watercourses, with the occasional large dead laurel tree and much tree heath. This species is highly mobile between different areas at different times of year. It was very abundant when the islands were first colonised by humans, but was extirpated. The losses on the islands were largely due to deforestation for wood and to create agricultural and grazing land. The exclusion of livestock from the native forest allows it to regenerate and create more suitable habitat. Some illegal hunting and poisoning continues because of the damage this pigeon can do to crops. Perhaps the main limiting factor on the rate at which the pigeon increases its numbers is eggs and young being taken by introduced black rats. It is now classed as Least Concern on the IUCN Red List, an improvement on its Threatened status in 1988. This species is protected under the European Union Birds Directive, and the laurel forests under the Habitats Directive. Taxonomy The genus Columba is the largest within the pigeon family, and has the widest distribution. Its members are typically pale grey or brown, often with white head or neck markings or iridescent green or purple patches on the neck and breast. The neck feathers may be stiffened and aligned to form grooves. One of several subgroups within Columba consists of the widespread Eurasian common wood pigeon, Bolle's pigeon, the Trocaz pigeon, and the African Afep pigeon. The two Macaronesian endemic pigeons, Bolle's and Trocaz, are thought to be derived from isolated island populations of