Merced National Wildlife Refuge, Nature reserve in Merced County, United States

Merced National Wildlife Refuge covers 10,262 acres of wetlands, native grasslands, vernal pools and riparian areas in Merced County, California. Shallow clay-bottomed pools fill with winter rain, then dry in spring and ring themselves with goldfields and purple owl's clover. About 300 acres grow corn and winter wheat, and over 500 acres of irrigated pasture are grazed by cattle and sheep under agreements with local farmers.

The refuge was established in 1951 under the Lea Act, after wintering waterfowl from adjacent farmland, where their foraging damaged crops, were drawn onto the site. Changes in farming practices and refuge management in later decades reduced those wildlife-crop conflicts.

This refuge is a gathering place where migratory birds from the far north make their winter home each year. Visitors can watch large flocks of cranes and geese that fill the wetlands with movement and sound.

Visitors can explore the refuge using an auto route and several walking trails that are open from sunrise to sunset year-round. The best time to visit is autumn and winter when bird populations are at their highest.

Vernal pools on the refuge fill with winter rain and hatch fairy and tadpole shrimp from cysts in the clay soil; as they dry, goldfields and purple owl's clover ring the basins, a display John Muir called the "floweriest part of the world" he had seen.