Current Change in the Winter Distribution of Red-crowned Grus japonensis and White-naped Grus vipio Cranes, Cholwon Basin Korea.

Pae, Seong-Hwan and Jeong-Chill Yoo

Department of Biology Kyung Hee University

130-701, Dong Dae Moon Gu Hoegi Dong 1

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Since 1883, cranes have been recorded by observations or collections in Korean Peninsula. Among the 15 Species of cranes belonging to the family of Gruidae in the order of Gruiformes, 7 species of cranes have their records in Cholwon Basin during the wintering or migratory seasons. Three species of cranes- Grus, japonensis, G. vipio, G. monacha- regularly migrate to Cholwon to winter. Four other vagrant species- G. canadensis, G. leucogeranus, G. grus, Anthropoides virgo - only occasionally appeared during the migratory seasons.

Our study was conducted between Oct. 1992 and Mar. 1998. The areas of the study, located in 38。 Our study was conducted Oct. 1992 and Mar. 1998. The areas of the study, located in 38。15'N and 127。13'E is the administrative districts of WolChol-ri and Taema-ri in the town of Cholwon and Hagal-ri in the town of Tongsong, Cholwon-Gun, Kangwon-Do. The study areas consists of mainly rice paddies and harvested grain fields (rice stubble) in Cholwon Basin (near DMZ) are the principal habitat types used by Red-crowned Cranes (Grus japonensis) and White-naped Cranes (Grus vipio) during spring and autumn migration and wintering seasons. Habitats available to migrant or wintering cranes on study area were divided into 9 sections such as Icecream Mountain (ICM), Cholwon Station (CWS), Whitehorse Monument (WHM), Taema-ri (TMR), Taejo-dong (TJD), Sangto-dong (STD), Chungto-dong (CTD), Hato-dong (HTD), and Meteorological Observatory (MO).

Wintering Red-crowned cranes were observed between 259 and 285, which were yearly stable. White-naped crane population were between 207 and 350, which trends are increasing. The proportion of time spent by both species in each habitat showed that ICM, CTD, CWS were regularly used by Red-crowned and White-naped Cranes for their wintering between 1992 and 1994. CWS and ICM have been known as the traditional wintering site, used for mail feeding site for migrant and wintering cranes. The habitat currently threatened are CWS feeding site and ICM adjacent to the Kangsan reservoir. New asphalt roads were constructed across the CWS and along the bank of the Kangsan reservoir. The trucks and buses with high speed drove cranes to move to other feeding sites. The daily habitat use indices of wintering cranes in CWS were changed from 15.51 (Red-crown Cranes) and 8.18 (White-naped Cranes) in 1992-94 to zero in 1997-1998, respectively. It means that feeding site available for cranes are decreasing and increasing competition for food resources.