The Hooded Crane Grus monacha remains the least known crane species in terms of its breeding range. Since 1985, typical wetlands meeting the characteristics of the typical Hooded Crane habitat have been surveyed between 56° and 66°N and between 108° and 136°E. Within the Lena River Basin, well-defined extensive breeding grounds of the Hooded Crane have been observed in the middle Aldan River Basin. Surveys of representative swampy headwaters, river reaches, and large watershed depressions, have revealed no other similar breeding grounds within the rest of the Lena River Basin, including areas attributed to the only known breeding grounds outside Manchuria. Within the extent of occurrence in the Lena River Basin and adjoining areas of the Olenyek, Khatanga and Yenisei river basins, breeding Hooded Cranes are presumably highly scattered. Solitary pairs are likely to breed hundreds of kilometers apart. Based on the distribution of wetlands, breeding grounds comparable to the middle Aldan River may occur in the basins of the upper Vilyui and the adjoining Moero and Kotui rivers. Evidence suggests that reports from local people are mostly plausible and consistent with maps and satellite images showing wetland habitat similar to that used by the Hooded Crane. Therefore, in the absence of direct data, the reports of the occurrence/nesting of Hooded Cranes beyond the Arctic Circle, particularly in the Olenyek River Basin quoted by Andreev (1974), should be given credence when delineating the breeding range. The region, including the Lena River Basin is too vast and difficult of access for aerial surveys to be practical. Tracking, based on navigation satellite systems, rather than stepwise ground surveys, is the only practical method for obtaining significant information over a short period of time.