Using satellite tracking and neckband resightings, Antti Piironen and Toni Laaksonen from the University of Turku, reveal in a newly published paper the existence and structure of a gradual migratory divide between the two European flyway populations of greylag geese; the NW/SW European population and the Central European population.

These important research results enable the allocation of the Finnish breeding population between the flyway populations. Moreover, using these results together with population size estimates, it is possible to estimate how many greylag geese from Finland belong to each of the two populations, and thereby increase the accuracy of the population size estimation and the range description of the flyway populations.

The paper is available online here: https://royalsocietypublishing.org/doi/10.1098/rspb.2023.1528