Tadorna tadorna, commonly known as the Common Shelduck, is native to parts of Europe and Asia. It is primarily found in coastal and inland regions across the northern and eastern parts of Europe, including the British Isles, the Baltic states, and extending eastward into parts of Central Asia, such as Kazakhstan and Mongolia.

The Common Shelduck typically inhabits coastal and estuarine areas, as well as inland wetlands. It prefers environments such as mudflats, sandbanks, salt marshes, and freshwater lakes with open shallow waters. These areas provide abundant food resources and suitable nesting sites.

Tadorna tadorna occupies a niche as a waterfowl in temperate and sometimes subtropical climates. The shelduck forages primarily on mollusks, crustaceans, and other small invertebrates found in the mudflats or shallow waters it frequents. The species is well-adapted to exploiting both aquatic and terrestrial feeding opportunities, which allows it to thrive in its specific niche.