Following a review and consultation by BOURC, the BOU adopted the International Ornithological Congress (IOC) World Bird List for all its ‘taxonomic needs’ from 1 January 2018 (BOU to adopt IOC World Bird List - British Ornithologists' Union), including for the British List. The initial decision to follow IOC was based significantly on the emerging collaboration between IOC World Bird List and eBird/Clements to harmonise global avian taxonomies. Seven years later and a unified global avian taxonomy – AviList – was published in June 2025, the product of collaboration between teams from BirdLife International, the IOC World Bird List, the eBird/Clements Checklist, AOS-NACC, and SACC as well as the Working Group on Avian Nomenclature (WGAC)’s own experts. Following this work, the IOC World Bird List will be discontinuing its independent taxonomic efforts in 2025–2026 such that the IOC List version 15.2 will be the last (About AviList – AviList: The Global Avian Checklist). The BOU intends to follow this new AviList taxonomy after IOC ceases updates at version 15.2. This change will have implications for the British List which will be detailed in the next BOURC report.

The BTO have announced they will adopt Avilist from 1 January 2026 which will presumably be the case for Birdtrack too!