The Grassland Wetlands of Merced County are a 25-square-mile complex of wetlands, ponds, and seasonal marshes in the western part of the county, including three national wildlife refuges (San Luis, Merced, and Kesterson). From October through March, the area supports huge populations of migratory waterfowl — sandhill cranes, Canada geese, white-fronted geese, pintails, wigeons, and teal — that use the wetlands as a wintering ground on the Pacific Flyway.
The best access points are the auto tour routes at Merced National Wildlife Refuge and the San Luis National Wildlife Refuge. Both have gravel driving loops through the marsh areas that allow birdwatching from a vehicle, which is the most practical approach given the scale of the area. Binoculars are essential; a spotting scope is useful. Peak numbers are typically in December and January, when counts of 100,000+ birds in a single day are not unusual.