Editing Western grebe (section)

==Description==
The western grebe is the largest [[North America]]n grebe. It is {{convert|55|-|75|cm|in|abbr=on}} long, weighs {{convert|795|-|2000|g|lb|abbr=on}} and measures {{convert|79|-|102|cm|in|abbr=on}} across the wings.<ref>[http://www.allaboutbirds.org/guide/Western_Grebe/lifehistory Western Grebe]. All About Birds</ref><ref name = "CRC">''CRC Handbook of Avian Body Masses'' by John B. Dunning Jr. (Editor). CRC Press (1992), {{ISBN|978-0-8493-4258-5}}.</ref><ref name="Burnie">Burnie D and Wilson DE (Eds.), ''Animal: The Definitive Visual Guide to the World's Wildlife''. DK Adult (2005), {{ISBN|0789477645}}</ref> It is black-and-white, with a long, slender, [[swan]]-like neck and red eyes. It is easily confused with [[Clark's grebe]], which shares similar features, body size, behavior and habitat, and [[Hybrid (biology)|hybrids]] are known. Western grebes nest in colonies on lakes that are mixed with marsh vegetation and open water. Western Grebe nests are made of plant debris and sodden materials, and the nest-building begins roughly around late April through June. The construction is done by both sexes and is continued on throughout laying and incubation.<ref>Mills, Kyra (2016)., "Post-Release Survival and Movement of Western Grebes (Aechmophorus occidentalis) Implanted with Intracoelomic Satellite Transmitters" {{ISSN|1524-4695}}</ref> This species of waterbirds is widespread in western North America, so there is no specific place of abundance. Its subspecies, Clark's grebe generally populate more of the southern part of North America <ref name="Kenn, Kaufman 2007">Kenn, Kaufman (2007)., Western Grebe. Birder's World, 21(6), 40–42.</ref> Other differences are whiter flanks and paler gray backs when comparing A.o.clarkii to A.o.occidentalis.<ref name="Ratti, J. T. 1979">Ratti, J. T. (1979). Reproductive Separation and Isolating Mechanisms between Sympatric Dark- and Light- Phase Western Grebes. American Ornithological Society, 93(3), 573–586.</ref> 
The western grebe has black around the eyes and a straight greenish-yellow bill whereas the Clark's grebe has white around the eyes and an up-turned bright yellow bill. The downy young of Western are grey; Clark's downy young are white.
<gallery mode=packed>
Western Grebe.jpg|alt=A western grebe walking on the shallows near a body of water|Out of the water
Aechmophorus occidentalis-swimming.jpg|alt=A western grebe swimming|Swimming
</gallery>

===Subspecies===

In 1858 [[George Newbold Lawrence]] recognised ''Podiceps occidentalis'' based on darker coloured specimens, and ''P. clarkii'' based on three paler coloured specimens -two from California and one from [[Chihuahua (state)|Chihuahua]]. These two colour [[Polymorphism (biology)|morphs]] were found to occur, roost and even interbreed together, and were long regarded to be synonyms (although it is unclear why ''P. clarkii'' was regarded as the junior synonym, coming alphabetically first). Deignan designated the Mexican specimen as the [[holotype]] of the taxon ''P. clarkii'' in 1961. In 1963 Dickerman reinstated the taxon as ''[[Aechmophorus clarkii]]'', which he defined as the smaller birds, both dark and pale coloured, from Mexico. In 1979 a comprehensive study by Ratti demonstrated the apparent existence of reproductive barriers between different phases of the grebes. In 1986 Dickerman recognised the taxonomic significance of the distinctions between the dark and pale phase, and classified these phases as different subspecies:<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>

*''A. occidentalis'' ssp. ''occidentalis'', <small>([[George Newbold Lawrence|Lawrence]], 1858)</small>, large, dark morph, from western Canada & United States (California, Utah)
*''A. occidentalis'' ssp. ''ephemeralis'', <small>Dickerman, 1986</small> - Smaller than the western grebe, dark morph, from north & central Mexico.
*''A. clarkii'' ssp. ''clarkii'', <small>([[George Newbold Lawrence|Lawrence]], 1858) Dickerman, 1963</small> - Small, pale morph, from north & central Mexico
*''A. clarkii'' ssp. ''transitionalis'', <small>Dickerman, 1986</small>, large, pale morph, from western Canada & United States (California, Utah)

Multiple lines of evidence suggest that the differently colored western grebes (darker and lighter) are different taxa -in a single population in which sympatric speciation somehow persists. These forms were reported to mate according to their own colors and the mixing between dark and light-faced individuals is rare.<ref name="Ratti, J. T. 1979"/> This type of assortative mating derives from possible isolating mechanisms such as differential responses to advertising calls and spatial distribution.<ref name="Ratti, J. T. 1979"/><ref>Storer, R. W., & Nuechterlein, G. L. (1985). Analysis Of Plumage and Morphological Characters of the Two Color Forms of the Western Grebe (Aechmophorus). American Ornithological Society, 102(1), 102–119.</ref> Each of the forms tended to stay closer to their own type, thus making their colony nesting be non-randomly distributed.<ref name="Ratti, J. T. 1979"/>

By 1992 Storer & Nuechterlein were promoting another concept to the taxon ''A. clarkii'', now regarding the pale morphs from the US and Canada to be this taxon (Dickerman's ''A. occidentalis'' ssp. ''ephemeralis'').<ref name=Storer1992>{{cite journal |title=Clark's Grebe (Aechmophorus clarkii) |url=https://birdsna.org/Species-Account/bna/species/clagre/foodhabits |journal=The Birds of North America Online |last1=Storer |first1=Robert W. |last2=Nuechterlein |first2=Gary L. |date=1992 |publisher=Cornell Lab of Ornothology, Ithaca, New York, USA |doi=10.2173/bna.26b |access-date=7 April 2017|url-access=subscription }}</ref>