The NHMO Avian collection at the Natural History Museum in Oslo, Norway is maintained and curated as four separate sub-collections, viz. the Preserved specimen, Eggshell, Sperm and DNA bank collections. In the collections database the sub-collections are, however, integrated and a single accession can contain items from one or more of the sub-collections. The Preserved specimen and Eggshell collections are traditional collections, dating back to the 17th and 18th centuries, respectively, while the DNA bank and Sperm collections were initiated only in towards the end of the 19th century (the DNA bank also contains some older material subsampled from e.g. the Preserved specimen collection).Most of the older parts of the collections have been collected during several scientific expeditions. In recent years, the main growth of the collection has come from the many blood and sperm samples collected as part of research projects in the Sex and Evolution Research Group (SERG) at the museum.The collection is databased in Corema, a software that has been developed in close cooperation between the NHMO and the developer, Digital Forvaltning AS (https://www.coremadb.com/). An accession generally refers to a given individual at a specific place and time; for each accession, one or more items may exist. Examples of item types include preserved skins, feathers or eggshells, blood, tissue or sperm samples, footage of live sperm motility, microscope slides prepared for sperm morphometric analyses, testes and extracted DNA.