Winter foraging of threatened cranes in the Demilitarized Zone of Korea: Behavioral evidence for the conservation importance of unplowed rice fields

We studied the winter foraging activity of the endangered Red-crowned crane (Grus japonensis) and the vulnerable White-naped crane (Grus vipio) in the Cheolwon area of the Civilian Control Zone (CCZ) area of South Korea, adjacent to the Demilitarized Zone with North Korea. Due to its limited development, the CCZ is one of the most critical migratory habitats for these endangered cranes. Farmers in the CCZ now plow most of their fields after the fall harvest rather than in the spring as they did previously. Cranes observed on the few remaining unplowed fields in the CCZ spent more time foraging than cranes on adjacent plowed fields. This behavior is a clear indication that the unplowed fields contain more food resources for the cranes than do the plowed fields. This is the first behavioral demonstration of differences in foraging between plowed and unplowed rice paddies for cranes in one of the cranes' most important refuges. We believe that the changes associated with plowing rice paddies may be detrimental to these threatened cranes, and efforts to promote unplowed fields in the CCZ should be encouraged.