The black-bellied plover (known in the rest of the world as Grey Plover) is a globally widespread shorebird commonly seen coastally when not breeding in the high arctic. It is the largest plover in America and a familiar sight.
The black-bellied plover has a global population four times that of the American Golden Plover. And, unlike the black-bellied, the golden plover does not overwinter in the US and is only seen briefly at stopover sites while migrating to South America flying thousands of miles; of which, 2,400 are over open ocean.
Golden Plover were shot heavily in the heyday of market hunting in the 1800's which was responsible for the decimation or extinction of many species (Read about Market Hunters at Wikipedia). Fortunately, Golden Plover are now classified as "Least Concern" and their numbers, while decreasing, are not considered to be in precipitous decline.
Coincidentally, the day this Golden Plover was photographed market the start of goose hunting season in Michigan and echoes of gunshot rang in the air as spooked migrants flew for cover.
In this collage of golden plovers at Lake St. Clair Metropark, different lighting shows the variation in exposure that can result. The one constant is the "dainty" look, finer bill, and long wings. However, two diagnostic features help distinguish the golden from the black-bellied: black armpits and white rump of the black-bellied are absent in the golden.
Shown here for example, are the rumps of the golden plovers -- clearly not white. Compare the daintier golden with the heavier black-bellied:
As can be seen, the differences are elusive; the bill is a good distinguishing feature but not conclusive. Two plovers in migration -- alike yet different in subtle ways -- offer both challenge and opportunity for those birding shorebird migration in the Fall.
Mid-September and Lake St. Clair Metropark can be a worthy hotspot for migrants as well as a testing ground for honing your identification skills!