The marshes support a variety of aquatic invertebrates, waterfowl, and other wildlife dependent on marsh habitat. At least 13 species of birds find the marshes suitable for nesting. Since 1988, the District has managed the McNabney marsh jointly with the East Bay Regional Parks District, the Contra Costa County Mosquito and Vector Control District and the California Department of Fish and Game. The bird watchers are the top recreational users of the marsh. The McNabney marsh entices wigeon, green-winged teal, sandpipers, shovelers, and pintail to feed and rest here during their winter migration.
Unusual birds show up in the fall through early spring.
In seasons past, red-shouldered hawks, stilt, sandpipers and European wigeons have visited the marsh. The McNabney marsh is part of the larger Peyton Slough Marsh complex. It has been cut off from the whole of the marsh since the early 1900's. This has restricted its ability to flood and drain with the tides and produced less than optimal conditions as a marsh habitat. This water sits on the soil and slowly evaporates.