Prioksko-Terrasny Nature Biosphere Reserve (Russian: Приокско-Террасный государственный природный биосферный заповедник) is one of Russia's smallest zapovedniks (nature reserves), sprawling over an area of 5,000 hectares along the left bank of the Oka River in the Serpukhov District of Moskva Oblast. It was established in 1945 as part of the Moscow Nature Reserve and is home to 900 plant species, 130 bird species, and 54 mammal species. A wisent nursery was established in 1948 to populate the region with European bisons from the Belovezhskaya Pushcha and Western Caucasus.