The Cheorwon basin located at the southern boundary of DMZ has been one of very important wintering areas of cranes in Korean peninsula. Many ornithologists have been monitoring wintering populations of Red-crowned Crane Grus japonensis and White-naped Crane Grus vipio since 1970's. But the wintering cranes have been threatened by diverse human disturbance in these days. The objectives of this paper are to investigate the trend of population change of wintering cranes and habitat distribution pattern in the area, and to analyze the causes of crane fatality mainly due to human disturbance. Data collected by our team since 2000 and previous reference data of others were employed.
The outcomes can be summarized as follows. First, the size of wintering population of cranes has been increasing steadily in the area. Red-crowned Crane’s population had reached to 800 in the latter half of 2000's, and White-naped cranes about 1,500 that the individual stays over the winter continuously. The crane’s distribution was 7.8km2 at 1980's but it was magnified steadily and 10 doubling quantity it was magnified with 76.7km2. The White-naped Crane increase tendency of latter half of 2000's appeared with the rapidly. Second, 42 individuals have been found to be suffered in 37 cases of accidents in this period. 19 individuals of Red-crowned crane were suffered in 14 cases, and 23 individuals of the White-naped crane were suffered in 22 cases. Third, major causes of accidents have been intoxication (31.0%), electric line collision (26.2%), iron fence collision along DMZ (14.3%), and unknown reason (18.4%). Other cause of accidents have been fracture (4.8%), exhaustion (4.8%), and gunshot wound (2.4%). Finally, conservation plan should include strict poaching control, density reduction of electric power lines, and the visibility enhancement measures of aerial obstacles such as attaching warning strips or electric bulbs to power lines and upper parts of iron fences along the DMZ.