Originally Posted by opisska
.... the suspects are Root, Field, Common and Pine?
Of these, I am not sure of the abundance of Pine Vole in north-east Poland.
In Lithuania, despite quite intense study (trapping and obtaining the skulls and hind foots for identification), there are no records at all of the species.
It certainly does occur in Poland, as well as further north than Lithuania, but the range seems to arc around the territory of Lithuania - without me actually knowing the range in Poland, it would be reasonable to suppose Siemanowka is somewhere near the edge of the known range, perhaps it does occur there, but perhaps not. And if it does, maybe the abundance is low ...or maybe not :)
Maybe ask in Polish institute for ecology.