I wonder if those are Castor fiber or canadensis?
We only have
Castor fiber here, the type subspecies from European Russia that was reintroduced here from a beaver farm near Voronezh a few decades ago and has been spreading since. Beavers were not a common sight 20 years ago but they are literally
everywhere now. They're spreading eastwards actively, and their presence is now a threat to the small remaining population of the Tuva beaver (ssp.
tuvinicus) one of the two Siberian subspecies, for some reason they are less robust and only live along a couple of smaller rivers in Tuva, which is adjacent to Mongolia. It's the same with the West Siberian beaver (ssp.
pohlei), a distinct, pale-colored northern subspecies limited to the river Sosva basin on the eastern slope of the Urals, which is now threatened by introgression from the introduced European subspecies. There are some
C. canadensis in northern European Russia, near the Finnish border, but none here in Siberia (yet).