Editing Grebe (section)

==Field characteristics==
Grebes are small to medium-large in size ranging from the [[least grebe]] (''Tachybaptus dominicus''), at {{convert|120|g|oz|abbr=on}} and {{convert|23.5|cm|in|abbr=on}}, to the [[great grebe]] (''Podiceps major''), at {{convert|1.7|kg|lb|abbr=on}} and {{convert|71|cm|in|abbr=on}}. Despite these size differences grebes are a homogenous family of waterbirds with very few or slight differences among the genera.<ref name="Winkleretal2020"/>

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| image1            = Diving grebe.jpg
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| caption1          = A diving grebe showing how the hindlimbs are propelling the bird underwater
| image2            = Zampullín a la carrera - Cabusset a la carrera - Little grebe running on water - Tachybaptus ruficollis.jpg
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| caption2          = A [[little grebe]] (''Tachybaptus ruficollis'') running along the surface of the water as it flaps its wings in order to get the lift it needs to fly
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===Anatomy and physiology===
[[File:Podiceps griseigena 238.jpg|A skeleton of a [[red-necked grebe]] (''Podiceps grisegena''). Note that the pelvic girdle is bigger than the sternum.|right|thumb]]

On the surface of the water they swim low with just the head and neck exposed. All species have lobed toes, and are excellent swimmers and divers. The feet are always large, with broad lobes on the toes and small webs connecting the front three toes. The hind toe also has a small lobe as well. The claws are similar to nails and are flat. These lobate feet act as an oar, as when moving forward they provide minimum resistance and moving backwards they provide a coverage of maximum surface. 

{{Multiple image
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| image1            = Grebe foot 1 (cropped).jpg
| image2            = Grebe foot 2 (cropped).jpg
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| footer            = Grebe foot, showing the lobed toes and strongly keeled tarsometatarsus
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The leg bones ([[femur]] and [[tarsometatarsus]]) are equal in length, with the femur having a large head and the presence of long cnemial crests in the tarsometatarsus. The patella is separate and supports the tarsometatarsus posteriorly which greatly helps with the contraction in the muscles. They swim by simultaneously spreading out the feet and bringing them inward, with the webbing expanded to produce the forward thrust in much the same way as frogs. However, due to the anatomy of the legs, grebes are not as mobile on land as they are on the water. Although they can run for a short distance, they are prone to falling over, since they have their feet placed far back on the body.<ref>{{cite journal |last1=Frank |first1=Harry R. |last2=Neu |first2=Wolfgang |title=Die Schwimmbewegungen der Tauchvögel (Podiceps) |trans-title=The swimming movements of diving birds (Podiceps) |language=de |journal=Zeitschrift für vergleichende Physiologie |date=1 September 1929 |volume=10 |issue=3 |pages=410–418 |doi=10.1007/BF00339264 |s2cid=31898176 }}</ref><ref name="Johnsgard1987" /><ref name="EoB">{{cite book |editor1-last=Forshaw |editor1-first=Joseph |last1=Fjeldså |first1=John|year=1991|title=Encyclopaedia of Animals: Birds|publisher=Merehurst Press|location=London|pages=59–60|isbn=978-1-85391-186-6}}</ref><ref name="Ogilvie2002" /><ref name="Fjeldså2004" />

The wing shape varies depending on the species, ranging from moderately long to incredibly short and rounded in shape. The wing anatomy in grebes has a relatively short and thin [[carpometacarpus]]-[[phalanges]] component which supports their primary feathers, while the [[ulna]] is long and fairly weak, supporting secondary feathers. There are 11 primaries and 17 to 22 secondaries, with the inner secondaries being longer than the primaries. As such grebes are generally not strong or rapid fliers. Some species are reluctant to fly. Indeed, two South American species are completely flightless. Since grebes generally dive more than fly, the sternum can be as small or even smaller than the pelvic girdle. When they do fly, they often launch themselves off from the water and must run along the surface as they flap their wings to provide a lift.<ref name="Johnsgard1987" />
 
Bills vary from short and thick to long and pointed depending on the diet, and are slightly larger in males than in females (though the sizes can overlap between younger males and females).<ref name="Ogilvie2002"/>

===Feathers===
Grebes have unusual [[feather|plumage]]. On average grebes have 20,000 feathers, the highest among birds. The feathers are very dense and strongly curved. In the larger species feathers are more dense but shorter, while the opposite is true in smaller species where the feathers are longer but less dense. 

The density and length of feathers is correlated exponentially with heat-loss in cold water. For this reason grebes invest plumage maintenance the most in birds in terms of duration of time and energy. The [[uropygial gland]]s secrete a high concentration of paraffin. The secretion provides a dual purpose of protecting the feathers from external parasites and fungi, as well as waterproofing them.<ref name="Fjeldså2004" />{{Rp|33–36}} When [[preening]], grebes eat their own feathers and feed them to their young. The function of this behaviour is uncertain, but it is believed to assist with [[pellet (ornithology)|pellet]] formation, excreting out internal parasites and protecting their insides from sharp bone material during digestion.<ref>{{cite journal|last=Simmons|title=Feather-eating and Pellet-formation in the Great Crested Grebe|journal=Br. Birds|volume=49|pages=432–435|year=1956|url=http://www.britishbirds.co.uk/search?model=pdf&id=3147|access-date=2013-02-22|archive-date=2016-04-15|archive-url=https://web.archive.org/web/20160415043309/https://britishbirds.co.uk/articles/search-articles/?id=3147&model=pdf|url-status=live}}</ref> The [[ventral]] plumage is the most dense, described as very fur-like. By pressing their feathers against the body, grebes can adjust their [[buoyancy]]. In the nonbreeding season, grebes are plain-coloured in dark browns and whites. However, most have ornate and distinctive breeding plumages, often developing chestnut markings on the head area, and perform elaborate display rituals.<ref name="EoB" /> The young, particularly those of the genus ''Podiceps'', are often striped and retain some of their juvenile plumage even after reaching full size.<ref name="Fjeldså2004" />{{Rp|36–39}}

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| image1            = Great Crested Grebe chick, Earlswood Lakes, Surrey (3522706435).jpg
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| caption1          = A [[great crested grebe]] (''Podiceps cristatus'') chick with its downy feathers and striped head
| image2            = 2016.10.30.-02-Wagbachniederung Oberhausen-Rheinhausen--Haubentaucher.jpg
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| caption2          = A great crested grebe in nonbreeding or winter plumage
| image3            = Пірникоза 6013.jpg
| caption3          = A pair of great crested grebe in breeding plumage as they perform a courtship ritual
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