Worldwide, there are 22 species of grebes, aquatic diving birds similar (though not related) to loons and auks. Seven, including the clark's and western (photographed below), are found in the United States. Also known as "helldivers," the birds are roughly the size of ducks, but share none of their affinity for flying, which grebes do clumsily and almost exclusively to migrate. With lobed feet on legs set far back on their bodies, grebes are built for swimming and diving.
During the spring, western and clark's grebes perform spectacular courtship dances. In the “rushing” display, the mating pair swim side-by-side with their wings held back, their long necks arched, and their yellow beaks angled upward. They swim so quickly that their bodies are pushed up out of the water and they appear to run across the surface. This courtship ritual functions as a reproductive isolating mechanism, one way of preventing the grebes from exchanging genetic material with birds of other species.
Once the courtship is over, the female will lay two to six eggs. Both male and female take turns to warm up and turn the eggs. It takes just over 20 days for the eggs to hatch.