The Checklist of alien birds of Belgium is a species checklist dataset published by the Research Institute for Nature and Forest (INBO). It contains information on 244 alien birds species occurring or ever observed in the wild in Belgium since 1800 and is is a compilation of different sources: literature (e.g. scientific papers, reports), citizen science portals (e.g. observations.be, waarnemingen.be, the Belgian Rare Birds Committee http://www.belgianrbc.be) and online databases such as DAISIE (DAISIE 2000) or the Global Avian Invasions Atlas (Dyer et al. 2017). Here, the checklist is published as a standardized Darwin Core Archive and includes for each species: the scientific name, higher classification and stable taxon identifier (in the taxon core), the presence in Flanders, Wallonia and the Brussels-Capital Region, as well as the year of the first introduction (first collection) and/or last assessment/observation in Belgium (given as a year range in the event date in the distribution extension), coarse ...