Eight Agami Herons (Agamia agami) captured in the Marais de Kaw-Roura National Nature Reserve in French Guiana were tracked with Argos satellite transmitters in 2012 and 2013. While nesting, birds used a 100- to 200-km² area around the colony site. After breeding, four birds moved from 280 to 1,250 km in different directions along the Atlantic coasts of Venezuela, Guyana, Suriname, French Guiana, and/or Brazil. Migration paths included one stop-over of 24 to 61 days. These results show that the Agami Heron uses large areas during the breeding season and can migrate long distances. That Agami Herons congregate from large areas into a limited number of potentially large colonies provides a basis for a conservation strategy for the species.