In a multiple year and multiple site study, long-tailed ducks were tracked with geolocators, revealing that the Baltic Sea remains the most important wintering site for the European population, underlining the observed drastic population declines in the Baltic.

Karwinkel, T., Pollet, I. L., et al. (2025). Individual Variation in Migration and Wintering Patterns of Long-Tailed Ducks Clangula hyemalis From a Population in Decline. Ecology & Evolution, e71187. https://onlinelibrary.wiley.com/doi/10.1002/ece3.71187

The short note on the migration of a Bluethroat (Blaukehlchen) from Central Siberia was now published in the Journal of Ornithology:
https://doi.org/10.1007/s10336-025-02270-8

This work was based on several years of fieldwork at two remote sites in Siberia - however, covid and the Russian war in Ukraine has hampered retrieval of loggers and therefore we can only present a single track. This bird used the Central Asian flyway to migrate to wintering grounds at the border between India and Pakistan, differing from an eastern Siberian Bluethroat which was tracked previously along the East Asian flyway, likely migrating through China to Myanmar. We speculate that a migratory divide exists somewhere west of the Yenisei river, separating populations of the same subspecies that migrate either east or west of the Qinghai-Tibetan plateau.

The paper was based on the Bachelor thesis of Sarah Strubbe, supervised by Nathalie Kürten (IfV) and Wieland Heim here in Oldenburg.

Migratory animals rely on multiple sites during their annual cycles. Deteriorating conditions at any site can have population-level consequences, with long-distance migrants seen as especially susceptible to such changes. Reduced adult survival caused by persecution at non-breeding sites has been suggested a major reason for the catastrophic decline of a formerly abundant, long-distance migratory songbird, the Yellow-breasted Bunting Emberiza aureola. However, it was unknown whether the ongoing extinction of this Eurasian species especially in the west of its range could be related to differences in survival or migration routes. 

In our new study, we investigated survival rates of populations from both western and eastern parts of the breeding range (based on colour-ringing) and successfully tracked the migration of individuals from two eastern populations (with light-level geolocators). We found moderate apparent local survival rates in eastern populations, but observed not a single returning bird in western populations. Our tracking data highlights (1) a joint migration corridor of eastern populations through eastern China, (2) long autumn stopovers likely used for moult and re-fuelling, and (3) very long occurrences at wintering sites. These areas should be given priority for future conservation measures. 

Heim W, Anisimov Y, Bastardot M, Davaasuren B, Nakul G, Anisimova V, Batbayar N, Beermann I, Dae We Aung T, Damrow L, Erdenechimeg T, Hahn S, Heim A, Heim RJ, Hölzel N, Kunz F, Levashkin A, Sander MM, Sankamethawee W, Thomas A, Kamp J (2024) Migration routes and adult survival of the Critically Endangered Yellow-breasted Bunting Emberiza aureola. Scientific Reports 14: 30593: [https://doi.org/10.1038/s41598-024-83138-4]