Gaining a clear picture of the status and trends of migratory birds is extremely difficult because these birds are so mobile and are influenced by numerous environmental conditions. Although we focus on the Chesapeake region, Bay population levels of ducks, geese, and swans are influenced by environmental conditions outside the region. For example, canvasback numbers in any given year may decline in the Bay because of drought conditions in the prairie pothole region where the ducks breed. The following information considers the status and trends of certain species, with the understanding that conditions in the Bay may satisfy only a portion of a species' needs during an annual cycle. Two species of swans, the mute swan and the tundra swan, are found on the Chesapeake Bay.
Tundra swans are native to the Bay region, but rely on the Bay only for wintering habitat.
Their populations have remained relatively stable. The mute swan, a common orange-billed swan found around the Bay in the summer, is not native to North America and is becoming a problem in Maryland. Control of mute swans is necessary to protect our native birds. The Canada Goose is the most abundant species of waterfowl on the Bay. The areas most attractive to these geese are large, open, grain fields close to water.