Many Amur-Heilong tributaries cross the region forming wetland-grassland landscapes that withstand the periodic droughts common in this climate. This cyclical climate fluctuation causes greater biodiversity and triggers migrations of many animal species. Lakes in the Mongolian steppe and throughout the western part of the basin are characterized by dramatic fluctuations in volume and area. Often they are dry depressions, sometimes with salt marshes. The total area and volume of lakes and wetlands in Inner Mongolia and Mongolia also changes according to climatic cycles.
Wetland habitats (many brackish or saline) exist throughout these grasslands and many are important breeding habitat for Whooper Swan (Cygnus cygnus), Swan Goose (Anser cygnoides, IUCN Endangered), Red-crowned crane (Grus japonensis, IUCN Endangered), and relict gull (Larus relictus, IUCN Vulnerable). The Mongol Daguur Strictly Protected Area, which covers the lower Uldz River basin with 90 small lakes, rivers, springs and wetlands, is the breeding and stopover place for many migrating birds including several rare species of crane. A large population of white-napped (Daurian) crane nests in wet areas of the steppes in the Ulz and Onon River valleys and in other valleys, which are important habitats for five other species of cranes as well.
Many species of fish and other aquatic species inhabit the Onon and Balj Rivers, including the Arctic lamprey eel (Lampetra japonica), Kaluga sturgeon (Huso dauricus), Khadary whitefish (Coregonus chadary), Haitej sculpin (Mesocottus haitej), Paracottus kessleri, river crayfish (Cambaroides dauricus), Dahurinaina dahurica, Rana chensinensi, and water snake (Natrix natrix).
Among China’s nature reserves Huihe National Nature Reserve is especially important for supporting populations of swan goose, cranes, and other wetland birds. A gazelle reserve west of Dalai Lake was established in China, while several reserves in the Kherlen River and Yakhi Lake basin exist within the Amur-Heilong basin in Mongolia.
The Russia-Mongolia-China Dauria International Protected Area (DIPA) was founded at the junction of the borders between Russia, Mongolia and China. The creation of this trilateral protected area, consisting of functionally connected wetland and steppe habitats, was of special importance for biodiversity conservation in Dauria, particularly for the protection of migrant species of birds and mammals.