Many of the migratory birds in Sweetwater Marsh feed in estuarine channels and saltwater ponds. More of them forage in sandflats and mudflats than on mudbanks, beach, or salt marsh areas. Shorebirds feed mostly on invertebrates found on and in the mudflats. Wading birds eat fishes and invertebrates found in the mud and sand. Diving birds feed mainly on fishes while dabbling ducks eat plants.
Plovers eat insects found around the mudflats and in the marsh.
While most birds are active during the day, many species make their annual migrations at night. These birds then feed and rest during the day. Also, by moving at night, the birds may reduce their chance of predation. Some species of ducks and geeses, gulls, pelicans, hawks and swifts do migrate during the day. Since many species of wading and swimming birds can feed at all hours, they migrate either by day or night and do not seek places to hide from predators.