Flyway connectivity and exchange primarily driven by moult migration in geese.

BACKGROUND

For the conservation and management of migratory species that strongly decrease or increase due to anthropological impacts, a clear delineation of populations and quantification of possible mixing (migratory connectivity) is crucial. Usually, population exchange in migratory species is only studied in breeding or wintering sites, but we considered the whole annual cycle in order to determine important stages and sites for population mixing in an Arctic migrant.

METHODS

We used 91 high resolution GPS tracks of Western Palearctic greater white-fronted geese (

RESULTS

Utilisation areas of the two populations overlapped only somewhat during spring and autumn migration stopovers, but much during moult. During this stage, non-breeders and failed breeders of the North Sea population intermixed with geese from the Pannonic population in the Pyasina delta on Taimyr peninsula. The timing of use of overlap areas was highly consistent between populations, making exchange possible. Two of our tracked geese switched from the North Sea population flyway to the Pannonic flyway during moult on Taimyr peninsula or early during the subsequent autumn migration. Because we could follow one of them during the next year, where it stayed in the Pannonic flyway, we suggest that the exchange was long-term or permanent.

CONCLUSIONS

We have identified long-distance moult migration of failed or non-breeders as a key phenomenon creating overlap between two flyway populations of geese. This supports the notion of previously suggested population exchange and migratory connectivity, but outside of classically suggested wintering or breeding sites. Our results call for consideration of moult migration and population exchange in conservation and management of our greater white-fronted geese as well as other waterfowl populations.

Déclaration de conflit d'intérêts

Approval for handling the geese was obtained in the Netherlands from the Animal Welfare Committee of the Royal Netherlands Academy of Arts and Sciences (DEC NIOO13.14), in Hungary from the Hunting and Fishing Department of Zala County Government Office (XX-H-004/1386–2/2012) and the Hunting and Fishing Department of Bács-Kiskun County Government Office (BKH/001/1135–2/2016) and in northern Germany (Lower Saxony) from the Lower Saxony State Office for Consumer Protection and Food Safety (LAVES AZ 33.19–42,502–04-15/1956 dated 15.9.2015).Not applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.