Editing Clark's grebe (section)

==Description==
[[File:Aechmophorus clarkii -Santa Margarita Lake, San Luis Obispo County, California, USA -family-8.jpg|left|thumb|A family in California, USA. Two chicks are riding on one parent's back]]
Clark's grebe closely resembles the western grebe and occurs in the same colonies together with it. Storer and Nuechterlein in 1992, following earlier morphological studies by Storer and others, define the species as being distinguished from the western grebe by an overall paler plumage on its back, as well as a larger portion of its face covered in white, as it extends above the eyes, rather than just below them. A distinguishing feature is its bill, which is bright yellow in the US, whereas the Western Grebe's bill is greenish-yellow in the US, which had been noted by others. Storer and Nuechterlein in 1992 claim that the bill is slightly upturned in this species whereas the western grebe has a straight bill, this was not noted in earlier studies.<ref name=Storer1992/>

The grebe has a long, slender neck and the species ranges in size from {{convert|22|-|29|in|cm}}, with a wingspan of {{convert|24|in|cm}}.<ref name=Storer1992/> Clarks' grebe has a weight range of {{convert|25.3|-|44.4|oz|g|abbr=on}}.<ref>{{Cite web|title=Clark's Grebe Identification, All About Birds, Cornell Lab of Ornithology|url=https://www.allaboutbirds.org/guide/Clarks_Grebe/id|access-date=2020-09-26|website=www.allaboutbirds.org|language=en}}</ref>

There are few changes between the sexes, the most notable feature that distinguishes males from females is the presence of a slight crest on the heads of males. In juveniles, the plumage is again similar to the Western Grebe, however it is also paler compared to the greyer Western species.<ref name=Storer1992/>

Its relative size compared to the western grebe is confused. Dickerman showed that grebes from the south of the range were smaller than northern examples, irrespective of which color morph, with both morphs being the same size depending on location, and Dickerman originally reinstated the name ''A. clarkii'' in 1963 for the smaller, southern populations (irrespective of which color morph). Studies by Storer, Ratti, Mayr and Short in the 1960–70s did not find any size differences between morphs. Nonetheless, some publications now state the paler-coloured grebes are slightly smaller, which might be due to confusion with the species concept advocated by Dickerman (in which Clark's grebe doesn't not occur in the USA or Canada, pale-coloured grebes in the US and Canada are western grebes, and dark-colored morphs in Mexico are Clark's grebe).<ref name=Storer1992/><ref name=Ratti1979>{{cite journal |last=Ratti |first=John T. |date=July 1979 |title=Reproductive Separation and Isolating Mechanisms Between Sympatric Dark- and Light-phase Western Grebes |url=https://sora.unm.edu/sites/default/files/journals/auk/v096n03/p0573-p0586.pdf |journal=The Auk |volume=96 |pages=573–586 |access-date=25 November 2018}}</ref><ref name=Dickerman1986>{{cite journal |last=Dickerman |first=Robert W. |date=1986 |title=Two Hitherto Unnamed Populations Of Aechmophorus (Aves: Podicipitidae) |url=https://www.biodiversitylibrary.org/page/34595906#page/463/mode/1up |journal=Proceedings of the Biological Society of Washington |volume=99 |pages=435–436 |access-date=25 November 2018}}</ref>

Although darker and lighter-colored morphs of grebes occur in the resident non-migratory populations occur in Mexico, it is unclear if these can be distinguished by the other morphological characteristics described above, as most studies have only looked at US populations. Lighter-colored morphs in Mexico are said to have orange-coloured bills, and the darker morphs have yellow bills. In the winter in California numerous examples of dark-colored western grebes displayed the mostly white face of Clark's grebe, although this was intermediate and thought to be possibly due to seasonal changes.<ref name=Storer1992/><ref name=Ratti1979/><ref name=Dickerman1986/>