Populations of Lesser Sandhill Crane (Grus canadensis canadensis) have been increasing during the last decades in Eastern Siberia, an area historically known as breeding grounds of endangered Siberian Cranes (G. leucogeranus). Significant overlap in niche dimensions between the two species may occur and could lead to competition between them. Therefore, this study of comparative breeding ecology of common Lesser Sandhill Cranes and endangered Siberian Cranes was performed. From late May to early August 2000, I studied Lesser Sandhill and Siberian cranes within a 30,000-ha part of Kytalyk Resource Reserve in the Republic of Sakha (Yakutia), Russia. My main objective was to compare dispersion patterns and resource use of breeding Lesser Sandhill and Siberian cranes in areas of distribution overlap. Lesser Sandhill Cranes used moderate-wet (polygon) areas as their nest sites and main foraging areas, where terrestrial foods were scattered. In contrast, Siberian Cranes were nesting and foraging on low-basin wet areas, where aquatic foods were concentrated and dominant. Inter-nest distances were less for heterospecific cranes than for conspecific cranes, and more territorial behavior was projected toward conspecifics than toward heterospecifics. Lesser Sandhill Cranes were more mobile and used moderate-wet (polygon) areas more than Siberian Cranes; however, both species spent similar time foraging and being alert. The two crane species used different vegetation types for nesting and foraging, had different time-activity budgets, and used different resources in the Siberian tundra. While the population of Lesser Sandhill Cranes in the study area has the potential to increase, both species may simultaneously share the same geographic area due to differences in ecological requirements.

Seasonal long-distance bird migration between wintering and breeding grounds is oneof the most remarkable phenomena in the history of life on earth. Migration strategies androutes vary greatly. Some birds migrate in social groups whilst others migrate alone at night,some cross few hundreds of km whilst others cover thousands of km. Avian migration has beenstudied extensively nevertheless numerous important questions remain unanswered. This studyaims to contribute to the understanding of the genetic basis of the innate migratory program ofa common songbird.From results of classical crossbreeding and orientation experiments with captiveblackcaps (Sylvia atricapilla) we can be sure that songbird migration directions as well asdurations are traits that are being inherited genetically and most likely have a multi-locusgenetic architecture. The chosen model species for my project is the willow warbler(Phylloscopus trochilus), one of the most common leaf warblers in the Palearctic. The willowwarbler has a continuous breeding distribution from the coast of the Atlantic to the coast ofPacific. They overwinter in sub-Saharan Africa. Three subspecies have been recognized: P. t.trochilus (breeding in central/western Europe and migrating SSW to western Africa), P. t.acredula (breeding in northern and eastern Europe, migrating SSE to east and south Africa)and P. t. yakutensis (breeding east of Ural Mountains, presumably migrating to SouthernAfrica). Morphological differences across the willow warbler subspecies are subtle and it has been previously shown that genome wide FST is close to zero. The low level of neutral back-ground divergence offers a good system for studying the genetics of passerine migration. This report contributes with novel data on phenotypes and genotypes of the subspecies yakutensisstudied at Chaun river delta, at the very eastern range limit of the species. As a proxy for thewintering location of yakutensis I used C and N stable isotope signatures from winter grownfeathers and inferred wintering range to be in Southern Africa. I genotyped 36 yakutensis fromChaun on four nuclear markers, of which three are located on the only divergent regions thatdiffers between the migratory phenotypes in Europe + CLOCK gene (a candidate for timing ofmigration). Analyzes revealed that yakutensis, despite strong differences in migration direction,distance, timing and wintering ground location cannot be separated from acredula genetically.