The uploaded dataset contains a classification of migratory behaviour for all 10596 extant species of birds (Aves). The dataset focuses on seasonal migration, i.e. movements causing an individual adult bird to be found in different locations over the course of one year, excluding every day routine movements (e.g. foraging movements) and one-way dispersal movements by juveniles (natal dispersal) or adults. Types or categories of migratory behaviour were recorded and classified from descriptions in the Handbook of the Birds of the World (del Hoyo 1992-2013 and updates on the Handbook of the Birds of the World Alive website www.hbw.com, accessed until September 2016). In addition to final species level classification of migratory behaviour, intraspecific variation in movement behaviours of each species was also classified. In the publication for which the dataset was used, we demonstrate the extent of migratory behaviour across birds as a whole and the impact this has on characterising climatic niches from distribution data. For future studies characterising climatic niches, we provide a framework for selecting appropriate occurrence data depending on migratory behaviour and data availability. In addition to the database, the upload includes a description of the methods used to classify species. Essential information of the rationale behind the dataset can be found in Eyres et al (2017).