Throughout this website, distributions are indicated by a code that is based on the following world-map scheme: 

The distribution of a given bird taxon is indicated by a matrix of nine boxes, with each box representing a defined region of the world. If a taxon does occur in a given region, the box representing that region takes the corresponding colour. White boxes indicate that a given bird taxon doesn’t naturally occur in that part of the world: 

The distribution code is most easily explained by a number of selected examples: