<P> The Alpine chough has an extensive though sometimes fragmented range, estimated at 1--10 million square kilometres (0.4--3.8 million sq mi), and a large population, including an estimated 260,000 to 620,000 individuals in Europe . The Corsican population has been estimated to comprise about 2,500 birds . Over its range as a whole, the species is not believed to approach the thresholds for the global population decline criteria of the IUCN Red List (i.e., declining more than 30% in ten years or three generations), and is therefore evaluated as Least Concern . </P> <P> At the greatest extent of the last glacial period around 18,000 years ago, southern Europe was characterised by cold open habitats, and the Alpine chough was found as far as south as southern Italy, well outside its current range . Some of these peripheral prehistoric populations persisted until recently, only to disappear within the last couple of centuries . In the Polish Tatra Mountains, where a population had survived since the glacial period, it was not found as a breeding bird after the 19th century . In Bulgaria, the number of breeding sites fell from 77 between 1950 and 1981 to just 14 in the 1996 to 2006 period, and the number of pairs in the remaining colonies were much smaller . The decline was thought to be due to the loss of former open grasslands which had reverted to scrubby vegetation once extensive cattle grazing ceased . Foraging habitat can also be lost to human activities such as the construction of ski resorts and other tourist development on former alpine meadows . Populations of choughs are stable or increasing in areas where traditional pastoral or other low intensity agriculture persists, but are declining or have become locally extinct where intensive farming methods have been introduced, such as Brittany, England, south - west Portugal and mainland Scotland . </P> <P> Choughs can be locally threatened by the accumulation of pesticides and heavy metals in the mountain soils, heavy rain, shooting and other human disturbances, but a longer - term threat comes from global warming, which would cause the species' preferred Alpine climate zone to shift to higher, more restricted areas, or locally to disappear entirely . Fossils of both chough species were found in the mountains of the Canary Islands . The local extinction of the Alpine chough and the reduced range of red - billed chough in the islands may have been due to climate change or human activity . </P>

Black bird with yellow beak and yellow legs