This annual update summarises and profiles some of the key developments in bird science and conservation during 2023. Since the last comprehensive edition of State of the World’s Birds was published in 2022, knowledge and evidence has continued to accumulate about the changing conservation status and trends of the world’s birds (STATE), the threats causing birds to decline (PRESSURE), and the conservation actions being taken to improve their status (RESPONSE).
BirdLife International is the official Red List Authority for birds, responsible for assessing and documenting the global extinction risk of all 11,000+ species for the IUCN Red List. Following transparent expert discussions on BirdLife’s Globally Threatened Bird Forums, the 2023 Red List update saw 11 species uplisted to higher threat categories due to a genuine deterioration in status, while just 4 were downlisted to lower threat categories due to an improvement in status. Many other species were reclassified for non-genuine reasons, such as better knowledge or taxonomic changes.
Among the species moved to higher threat categories were several island endemics suffering the impacts of invasive species. Two of Hawaii’s honeycreepers—Anianiau Magumma parva and Kauai Amakihi Chlorodrepanis stejnegeri—moved from Vulnerable to Endangered following estimated population declines of more than 60% during 2008–2018, largely as a result of avian malaria carried by introduced mosquitos. Elsewhere, Juan Fernandez Tit-tyrant Anairetes fernandezianus, endemic to Robinson Crusoe Island off the coast of Chile, was uplisted from Near Threatened to Endangered after invasive plants and introduced predators drove rapid population declines.
Forest loss also continues to drive population declines worldwide. Citron-throated Toucan Ramphastos citreolaemus was moved from Least Concern to Near Threatened due to the ongoing effects of forest loss in South America, while in South-East Asia, Cinnamon-rumped Trogon Harpactes orrhophaeus was uplisted from Near Threatened to Vulnerable due to loss and fragmentation of its lowland forest habitat.
However, downlisted species provide reasons for hope, showing the positive impacts of conservation actions. Thanks to local community efforts to conserve habitats and prevent persecution, three Asian stork species—Greater Adjutant Leptoptilos dubius, Lesser Adjutant Leptoptilos javanicus and Painted Stork Mycteria leucocephala—were moved to lower threat categories. In Hawaii, successful translocation of Millerbird Acrocephalus familiaris from Nihoa to Laysan during 2011–2012 has resulted in a self-sustaining population, warranting downlisting of the species from Critically Endangered to Endangered.
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