Abstract
To study the relationship between plant communities and nest site selection of Tancho (Grus japonensis) in the Kushiro Mire, eastern Hokkaido, vegetation at the area covered by a nest, and about 100 ha circle around nest (buffer circle) was analyzed by using a vegetation map and the locations of the nests located by aerial surveys during the 2000-2009 period. Nests were found on 26 types of vegetation. The largest number of nests were in the alder (Alnus) community (27.8% N=916), and then in the tall reed (Phragmites- Calamagrostis) community (23.3%). Finally total 84.5% of nests were found on the alder dominated and the reed dominated communities. However, nesting vegetation types recorded in common with the core and the peripheral regions of the Kushiro Mire were few except alder and reed communities, and nests were much more found in terrestrial forest communities in the peripheral regions rather than those in the core region. Though vegetation types in a buffer circle around each nest varied at each site, the average composition of vegetation types in buffer circles of all nests was quite similar to that of core region of the Kushiro Mire. As vegetation types at nesting spots of new breeding pairs did not basically differ from those of successive breeding pairs, it is suggested that types of vegetation was not an absolute factor for nest site selection of the cranes. The results of this analysis seemed useful to apply for the conservation of potential habitats which are not yet protected in Hokkaido, although there were some discrepancies between the vegetation maps and actual nesting habitats shown by aerial photographs.
