Abstract
Stopovers along the flyway of the Siberian Crane in the taiga zone of northeastern Asia have not been previously described. In this study, we provide the first investigation of the stopovers of its eastern population in the taiga zone (2006-2011). Seven spring stopovers at bogs were investigated for 10-24 hr each. The birds spent 5-6 hr sleeping at night, while 54-74 % of their time was spent foraging outside the sleep time budget. Based on excreta samples, only 5/109 cranes successfully obtained adequate food during stopovers at typical bogs. Favorable foraging conditions were found at the rare shallow lakes or at Elk Alces alces salt licks where the foraging efficiency was 16 times greater than at bogs unaffected by ungulates. Elk activity led to areas of peat exposure in bogs where the availability of edible grass rhizomes and readily extractable sprouts were increased for the Siberian Crane. Investigations at three autumn stopovers at poor forage riverbeds lasted for 0.3-11.0 hr and were interrupted by boating activities, as were 22 other reported stopovers. Cranes allocated a high proportion of their time to foraging, which they commenced immediately after landing. However, the cranes failed to acquire any significant sustenance during the overwhelming majority of taiga stopovers. Our investigation showed that the eastern population was not specialized in foraging at typical taiga wetlands. Humans indirectly aggravated the naturally harsh migration conditions by overhunting Elk on the flyway and intensive boating activities during the most intense migration period.
Highlights
Stopovers along the flyway of the Siberian Crane in the taiga zone of northeastern Asia have not been previously described
Wetlands utilized by the population The Siberian Cranes stopped at marshes around flood plain lakes, at river gravel spits or flats, and at bogs that differed in their distribution, total area, and density (Table 1), as well as extremely rare shallow lakes
After visiting 12 reported stopover locations, we found that a marsh, two shallow lakes, two bogs, and four areas by the main stream were typical habitats, which were utilized by Siberian Cranes as described above
Summary
Stopovers along the flyway of the Siberian Crane in the taiga zone of northeastern Asia have not been previously described. We provide the first investigation of the stopovers of its eastern population in the taiga zone (2006–2011). Elk activity led to areas of peat exposure in bogs where the availability of edible grass rhizomes and readily extractable sprouts were increased for the Siberian Crane. Investigations at three autumn stopovers at poor forage riverbeds lasted for 0.3–11.0 hr and were interrupted by boating activities, as were 22 other reported stopovers. Our investigation showed that the eastern population was not specialized in foraging at typical taiga wetlands. Humans indirectly aggravated the naturally harsh migration conditions by overhunting Elk on the flyway and intensive boating activities during the most intense migration period
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