From 2026 onwards, the English names and scientific names of birds in the series of ATWB Companion Guides will be derived from The Global Avian Checklist, an open access resource maintained by the AviList Core Team. The AviList is hosted on a dedicated website, which provides access to the checklist in two formats.

The AviList is updated once a year. The version of the AviList that will be used in the 2026 versions of ATWB guides is v2025, published June 2025.

AviList Core Team. 2025. AviList: The Global Avian Checklist, v2025. https://doi.org/10.2173/avilist.v2025

Alongside the Checklists, the AviList Core Team has provided a register of corrections, v2025 errata, which can be found here. The corrections that are available at the time of publication will be incorporated into the ATWB 2026 series of Companion Guides.

Note that species in the AviList that are annotated as being either extinct or possibly extinct will not be included in the ATWB series of Companion Guides. Hence, the term ‘extant’ that may appear for some families in the guides should be interpreted as implying ‘known to be extant’.