Two years since its previous update, the eBird/Clements Checklist of Birds of the World has just published the August 2021 update, and is now available in BUBO Listing.
This major update has 17 newly-described species, 94 new splits, and 8 lumps. Most of these have already been implemented by IOC if you follow that for your world list. A good summary of the changes is provided by eBird, and a discussion of them in our forum.
We automatically apply updates where we can, and in other cases you will be prompted for any taxonomic changes to address yourself.
If you have any queries about distributions or identification of individuals so that you know what you can count, do post in the forums so that other BUBO Listers can help out.