Migration patterns and conservation status of Asian Great Bustard (Otis tarda dybowskii) in northeast Asia

The Great Bustard (Otis tarda) holds the distinction of the heaviest bird to undertake migration as well as the greatest degree of sexual size dimorphism among living birds. Though the migration of the species has been widely discussed in the literature, researchers know little about the migration patterns of the subspecies in Asia (Otis tarda dybowskii), especially the males. In 2018 and 2019, we captured six O. t. dybowskii (five males and one female) at their breeding sites in eastern Mongolia and tagged them with GPS-GSM satellite transmitters. This constitutes the first time that the Great Bustards of the eastern subspecies have been tracked in eastern Mongolia. We found sex differences in migration patterns: males started migration later but arrived earlier than the female in the spring; males had 1/3 of the migration duration and migrated about 1/2 the distance of the female. Additionally, Great Bustards exhibited high fidelity to their breeding, post-breeding, and wintering sites. For conservation, only 22.51% of GPS location fixes of bustards were within protected areas, and less than 5.0% for wintering sites and during migration. Within two years, half of the Great Bustards we tracked died at their wintering sites or during migration. We recommend establishing more protected areas at wintering sites and rerouting or undergrounding powerlines in areas where Great Bustards are densely distributed to eliminate collisions.