With the exception of the trends by habitat, the tables of population change that appear on the species pages in BirdFacts are species-based selections from a single unified table, with data newly calculated to include data up to and including 2021. A number of additional selections from this table, by scheme and time period, are presented in the Summary tables and Discussion sections.

This edition of the BirdTrends report is the latest in an annual series that began in 1997. Citations for previous editions are listed under Previous reports. Links are given to the full text of previous reports, which are mostly still available online.

The Utilities section also holds a unified list of the References that have been cited throughout the report.