The ecology of the habitats, nesting, and migration of the eastern population of the siberian crane (Grus leucogeranus Pallas, 1773)

The structure of the distribution range and population of the Siberian crane in its regular breeding area in the northeastern Yakutian tundra are described, as well as the migration terms, intensity, routes, and stopover sites. The territorial pairs (71.7–97.1% of the summer population), which in 2006 were represented by the birds at ages of 8 to 21 years (mainly 20 years, accounting for 45.4%), constantly stayed on an area of 7.3–16.5 km² independently of their participation in breeding. The breeding success in this population varies from 4.3–8.7 to 65.0–83.3% and depends on the climatic conditions at the beginning of egg laying; these climatic conditions change rather unpredictably from year to year, as well as being seasonally unstable. This explains that fact that some generations in this population are particularly vulnerable to natural elimination factors because of their low numbers. Bird migration in Yakutia follows a narrow tunnel with the highest migratory intensity in the Middle Aldan Valley. In the fall, 30 to 50% of the entire population is visually recorded there.