Colombo, Jan 23 : Sri Lanka's Biodiversity Secretariat said that 81 of the country's bird species are at risk of extinction. Director of the Biodiversity Secretariat R.H.M.P. Abeykoon told local media that Sri Lanka is a biodiversity hotspot with 435 species of birds, and this has been found during a nationwide survey on the Red Data Book of 2022, reports Xinhua news agency. The birds are faced with the threat of extinction owing to the damage caused to their habitats by humans, she said. The Red Data Book is a public document recording endangered and rare species of plants, animals, fungi as well as some local subspecies that are present in a particular region. Sri Lanka is currently home to around 237 resident birds, at least 26 of which are endemic species. Apart from this, the island nation is also visited by a number of migratory birds. The 2007 IUCN Red List on Sri Lanka lists 10 species of birds as critically endangered, and a number of others as endangered and vulnerable. /IANS