This species nests on large inland lakes in western North America and migrates to the Pacific coast over the winter.

It maintains local populations year-round in California, Nevada, and Arizona (the Lower Colorado River Valley), as well as in central Mexico.

[2][10][11] Clark's grebe (Aechmophorus clarkii) is a waterbird of the family Podicipedidae in the order Podicipediformes, which are related to flamingos.

[12] This taxon is extremely similar to the western grebe: it has the same behaviour, including the elaborate courtship displays, occurs sympatrically in the same range and has the same migrations, and is morphologically almost alike, with this bird most noticeably being somewhat paler in colouration.

As such, it was commonly thought to be a paler-colored morph (a version with paler colours and more white), as occurs in many bird species.

[10][11] After the presence of this taxon throughout the range of the western grebe was discovered, along with the identical behaviour, the two taxa were synonymised, and this situation was accepted by ornithologists throughout the first half of the 20th century.

His studies showed that there was little overlap in size measurements between Mexican and northern populations -irrespective of coloration; as such Dickerman's 1963 view was that A. clarkii are smaller grebes restricted to Mexico, which might be found in either light or dark morphs, and A. occidentalis are larger-sized, migratory grebes from the US and Canada also found in two colour morphs.

[11] A study in 1979 based on late 1970s observations of pairs the birds courting or nesting, however, noted that the frequency with which two different colour morphs were seen together or were found nesting together was much lower than one would expect if the pairings were random, some reproductive isolating mechanism was keeping the taxa separate.

There was also a marked difference in reproductive success in the study area, with Clark's grebe being initially quite low in frequency at around 12%, but increasing to a third of the population of both taxa in a three-year period.

[11] By 1992, Storer and Gary L. Nuechterlein, both having studied the grebes in the 1970s, recognised the paler-coloured morphs in the US and Canada in the book The Birds of North America as A. clarkii, thus apparently rejecting Dickerman's species concept and subspecific classification, although they do not explicitly state this, and because this work does not include Mexico as part of North America, his work is not actually in their remit.

[2] Clark's grebes occur seasonally throughout the majority of Western America, with a distribution ranging as far south as Mexico, and reaching as far north as British Columbia and Saskatchewan.

[2] Storer and Nuechterlein in 1992 dubiously claim the birds winter in Central America, as well as in Mexico and some regions of California.

These two distributional areas representing where grebes have ever been seen only meet each other in the very north of Mexico in a strip along the USA border, to the south they do not come together and are separated by a very large distance.

Thought to be a fish specialist in the early 20th century as a result of the examination of their pellets and stomach contents, it was shown by 1962 that Clark's grebe is actually an opportunist when it comes to the food it eats, and is less picky with its selection than previously imagined.

This means that the species will actually consume a wide variety of things such as salamanders, crustaceans, polychaete worms and insects while diving and foraging for their preferred small fish, so long as they fit the size constraints of the bill.