The horned grebe or Slavonian grebe (Podiceps auritus) is a relatively small and threatened species of waterbird in the family Podicipedidae. The Eurasian subspecies is distributed over most of northern Europe and northern Asia, breeding from Iceland east to the Russian Far East. The North American subspecies spans most of Canada and some of the United States. A small population was cited in Greenland in 1973, from Sclavonia, an old name for northern Prussia, referring to the species' main breeding area in Europe; the spelling was emended (without any reason given) to the current 'Slavonian' by Hartert in 1912.
Taxonomy
The horned grebe was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Colymbus auritus. Linnaeus specified the type locality as Europe and America but this has been restricted to Vaasa in Finland. The horned grebe is now one of the nine species placed in the genus Podiceps that was introduced in 1787 by the English naturalist John Latham. The genus name combines the Latin podex meaning "vent" and pes meaning "foot". The specific epithet auritus is Latin meaning "-eared" or "long-eared", and the subspecific name cornutus means "horned".
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Slavonian Grebe (Podiceps auritus auritus) juvenile Kaldbakstjarnir.jpg|juvenile P. a. auritus
Slavonian Grebe (Podiceps auritus auritus) immature Kaldbakstjarnir.jpg|immature P. a. auritus
Slavonian Grebe (Podiceps auritus auritus) breeding Kaldbakstjarnir 1.jpg|adult P. a. auritus in moult from breeding to winter plumage, calling
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Description
The species can be recognised by its orange-red and black breeding plumage, its black and white non-breeding plumage, and its characteristic "horns". It is long, has a wingspan wide and weighs . and the northern tier of west-central contiguous USA states from northeastern Washington to Minnesota || Inshore waters of the Pacific and Atlantic coasts of North America, from southern Alaska south to California and the northern Gulf of California, and Nova Scotia south to Texas.
A third subspecies P. a. arcticus <small>Boie, 1822</small> has sometimes been accepted for the population in coastal Norway, Iceland, and Scotland,
Vocalisation
Young begin calling for begging purposes in a slightly trilled peeping noise, similar to that of a domestic chick. As they mature, their song changes to a more adult-like chittering. They use other calls during copulation, alarm and breeding ceremonies that are slightly variable from the advertising call. Horned grebes are extremely vocal during breeding, territory establishment and defence. This habitat provides a suitable site for nest material, anchorage, concealment and protection for young. It readily uses lakes surrounded by trees or forest. During the summer, aquatic and airborne arthropods are preferred, whereas winter selection favours fish and crustaceans. The discovery ceremony begins with advertising displays, which include an upright posture, erect "horns" and sounding of their advertising call. Then, both male and female engage in bouts of penguin dance and preening. This initial pair bonding ceremony is to ensure correct species identification, sex and compatibility. which are coloured white, brownish or blueish green. Both males and females share incubation time for 22 to 25 days. The species finally reaches sexual maturity at two years old.
Fossils
A handful of fossil species, such as the Pliocene aged P. howardae, P. pisanus and P. solidus, and the Pleistocene aged P. dixi have been described to be related to or perhaps some of them might be pre-Holocene material of the horned grebe. However while P. howardae and P. dixi are regularly recognized as fossil material of the horned grebe by some authors, P. pisanus and P. solidus are argued to be valid species that are close to the ancestry of the horned grebe.