In breeding plumage, Black-bellied Plovers are a dazzling mix of snow white and jet black, accented by checkerboard wings. They are supreme aerialists, both agile and swift, and are readily identified at great distance by black axillaries (“armpit” feathers) in all plumages—and by their distinctive, mournful-sounding call. The largest and heaviest of North American plovers, Black-bellied is also the hardiest, breeding farther north than other species, at the very top of the world. It is also a very widespread shorebird, occurring on six continents.
https://www.allaboutbirds.org/guide/Black-bellied_Plover/overview