We investigated the application of satellite tracking to the conservation of cranes and other waterbirds and the necessity of international cooperation in the conservation of migratory species. Using satellite tracking, we followed 11 White-naped Cranes (Grus vipio) on migration from their breeding grounds in eastern Russia to their wintering grounds in China and Japan. From 1991 to 1993, we captured cranes with the aid of helicopters and attached satellite transmitters (platform transmitter terminals) to captured birds via a harness system. We tracked cranes for 156 days on average, across 2558 km, and obtained an average of 339 locations per crane. Cranes migrated over 8-90 days. During migration, birds spent 1-30 days at 4-12 rest sites. Cranes wintered at two main sites: Poyang Lake, China, and Izumi, Japan. All seven cranes migrating to the Poyang Lake area rested at the Yellow River delta-Bohai Bay, China, and all three traveling to Izumi rested in the Demilitarized Zone on the Korean Peninsula. Other important rest sites were marshes around the Wulagai River, Huainan, Hu-Lun Lake, Linyi, Tangshan, the Three Rivers (Sanjiang) Plain, Tianjin, and the Xar Moron River, all in China, and Lake Khanka-Xinghai at the border of China and Russia. The habitats resting cranes used most frequently were plains, including upland areas, marshes, and rivers. Although nature reserves exist at the two main wintering sites of Poyang Lake and Izumi, rest sites used by cranes were poorly protected. Even when areas used by cranes for resting or wintering were included in nature reserves, reserves were threatened by human encroachment and development. To ensure that cranes can continue to migrate successfully, it is crucial that the establishment of reserves continues at important rest areas and that the areas covered by reserves at wintering sites be extended to include more of the areas utilized by cranes. Also, development and human disturbance should be minimized in reserve areas. Because long-distance migrant birds, including cranes, range over such large areas, conservation of these organisms and their habitats necessitates multinational communication and cooperation. Resumen: Investigamos la aplicación del rastreo por satélite a la conservación de grullas y otras aves acuáticas y la necesidad de cooperación internacional en la conservación de especies migratorias. Utilizando el rastreo por satélite, seguimos la migración de 11 grullas de nuca blanca (Grus vipio), desde susáreas de reproducción en Rusia oriental hasta suárea de hibernación en China y Japón. De 1991 a 1993 capturamos grullas con la ayuda de helicópteros y les colocamos transmisores de satélite (terminales de transmisor de plataforma) mediante un sistema de arnés. Rastreamos a las grullas por 156 días en promedio, a lo largo de 2558 km, y obtuvimos un promedio de 339 localidades por grulla. Las grullas migraron por 8-90 días. Durante la migración, las aves estuvieron de 1-30 días en 4-12 sitios de descanso. Las grullas invernaron en dos sitios principales: L...