White-fronted Geese on passage

Yesterday there where White-fronted Geese present on several locations in my local area. The clear morning sky saw a flock of 60-70 flying northwards rather high up at Asköviken. I heard their piercing calls from far away. Later in the afternoon at least 250 birds where staging/ feeding near Hjälstaviken together with some Bean Geese and Barnacles too. I find these birds fascinating (the White-fronts). Not only have they increased noticeable in the last decades (used be a scarce bird or at least not numerous), but they also tend to stay longer in spring, especially the 100 or so that stage every spring in the Black River Valley. They often linger well into May and stay behind weeks after the more early Bean Geese. That makes me wonder where these birds actually breed? How far into Russia do they fly? Because certainly they don´t breed in Scandinavia. It would be interesting if somebody could raise some funds and start a project to put some transmitters on a few of the White-fronts on spring passage in the Black River area for instance!