Ecology of the eastern population of the Siberian Crane Leucogeranus leucogeranus in the taiga section of its flyway: habitats, foraging, trophic links with Elk Alces alces, and threats

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.