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Described to science in 1858, Clark's Grebe was soon dismissed as a mere variant of Western Grebe, and thereafter was ignored for over a century. Studies in the 1970s and 1980s showed that Western and Clark's, though extremely similar, are actually two distinct species. Minor differences in face pattern, bill color, and voice seem to be enough to prevent the two from interbreeding most of the time, even where they nest in mixed colonies. Apparent hybrids have been found, but they are a minority of the population. Although Clark's may be found with Western Grebes at all seasons, it tends to associate more with its own kind. In almost all aspects of behavior that have been studied, Clark's Grebe seems identical to Western Grebe. In one study on lakes in Oregon, Clark's tended to feed farther from shore and in deeper water.