This is a Romanian hamster (Mesocricetus newtoni). It is found in Bulgaria and Romania near the Black Sea.
It was heavily persecuted because of its depredations on agricultural enterprises, and it is now regarded as “near threatened” by the IUCN.
I don’t know how to distinguish this species from the golden hamster.
If it’s running in the wild in Romania or Bulgaria, that might give me a clue.
But other than that…
I should note that this species has a gestation period of only 15 days. Golden hamsters have a gestation of 16 days, which means that the Romanian hamster has the shortest gestation period of any placental mammal.
