Periodically the International Ornithological Congress updates the global list of bird species based on advances in the understanding of the relatedness of bird species.

The British Ornithologists’ Union, who maintain the official list of British birds, follows IOC changes. Furthermore, BOU reviews records of species new to Britain, and periodically reviews old records if new evidence comes to light. 

All these processes can change the list of species deemed to have occurred in the UK, with consequences for the list of species covered by BirdFacts. This page lists those changes, with links to the BOU publication detailing the reasoning.

January 2023

July 2022

January 2022

January 2021

  • Subalpine Warbler split into Eastern Subalpine Warbler and Western Subalpine Warbler, both added to category A of the British List.


  • Subalpine Warbler split into Subalpine Warbler and Moltoni's Warbler, with the latter added to category A of the British List.

April 2006

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