Since 1886, a committee of the American Ornithologists’ Union—now called American Ornithological Society, or AOS—has been responsible for keeping the official, standardized list of North American bird species. Every summer this committee, usually referred to as the AOS Checklist Committee, publishes a supplement to summarize their latest work. This may result in changing some names or changing how some birds are classified, with two or more species being combined (“lumped”) into one, or with one species being separated (“split”) into two or more. Avid birders watch for this annual report to see if it will change their own personal life lists. The 2024 supplement, published online in July, revealed an exceptionally active year for changes to names and classifications. For birders in the United States and Canada, the most notable shifts this year are the lumping of Common Redpoll and Hoary Redpoll into one species, the split of Brown Booby into two species, and the...