The Pacific Flyway consists of several parallel routes. Wetlands and coastal bays are stop-over sites for resting and feeding. If these birds could not eat and rest in wetlands, they would not have the energy needed to complete their migration and they could die. 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.