Abstract
The core of any taxonomic checklist comprises species‐level delimitations. These should be made as consistent as possible among different taxa, within a single checklist but also between checklists and major taxonomic groups, and thus follow a common framework. This concise text explains the guidelines for species delimitation applied in the process of gradually updating the Howard & Moore Complete Checklist of the Birds of the World (4th Edition) as it evolves into an online list with continuous updating. This text is not aimed at providing a comprehensive review on different species concepts and species delimitation procedures, but instead explains the basis used in the Howard & Moore Checklist for assessing species rank of valid taxa. It is not an entirely new or original approach, as it draws its foundations from previous publications on speciation, species concepts or guidelines for taxonomic decisions and has previously been employed in other groups of animals (e.g., Speybroeck et al., 2020).