The five million bird eggs in the world's museum collections are an invaluable and underused resource

The similar to 1.97 million egg sets (similar to 5 million eggs) housed in museums have not been used in proportion to their availability. We highlight the wide variety of scientific disciplines that have used egg collections and the geographic locations and sizes of these collections, to increase awareness of the importance of egg collections, improve their visibility to the scientific community, and suggest that they offer a wealth of data covering large spatial scales and long time series for broad investigations into avian biology. We provide a brief history of egg collections and an updated list of museums/institutions with egg collections worldwide. We also review the limitations, challenges, and management of egg collections, and summarize recent literature based on historical and recent museum egg materials.