Successful conservation of migratory birds relies on coordinated management across international borders. Here, we determined the geographic and taxonomic coverage of international agreements aimed at protecting migratory birds. We identified 49 international migratory bird agreements spanning 187 countries and covering 1,677 (86%) of the world’s 1,958 migratory bird species. Fewer such agreements were located in middle-income countries characterized by less effective governance, small size, and few bordering countries. Threatened species were listed in fewer agreements than non-threatened species. Waterbird species tended to be listed individually by species name, while non-waterbird species tended to be covered implicitly through the listing of higher taxonomic ranks such as Families or Orders. Of the migratory bird species, only 28% had all their range countries participating in at least one agreement, while 14% had none. With large geographic gaps remaining, much work needs to be done to expand the global network of migratory bird agreements.