''Aechmophorus''

Etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

: ''Aechmophorus'', "spear-bearer", from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''aichme'' (a spear) + ''phoros'' (one who bears something around), in reference to its bill. is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s in the

grebe Grebes () are aquatic diving birds in the order Podicipediformes . Grebes are widely distributed freshwater birds, with some species also found in marine habitats during migration and winter. Some flightless species exist as well, most notably ...

family.

Species

It has two living representatives breeding in western

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. One prehistoric

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

has been described from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

remains: *''Aechmophorus elasson'' (Late Pliocene of W USA) Although the two living species look very similar,

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Plac ...

shape and coloration, as well as feathering around the scarlet eye of the bird can be used to determine the precise species.

Distinguishing features

The western grebe has a straight bill with a dull green-yellow color as opposed to the Clark's grebe, which has a slightly upturned, bright orange-yellow bill. In both species the male has a longer and deeper bill than that of the female, making it a distinguishing feature. All species of grebes display the pattern of lobed feet. A tough skin surrounds each toe separately, providing more surface area for effective swimming. This form increases the power of propulsion per stroke and reduces drag when the bird is recovering. Skeletal measurements taken from both species, when averaged together, revealed that for the most part the western grebe is larger than the Clark's grebe. The two species also differ in their advertising calls. The western grebe gives a call that includes two distinct “cree-cree” notes, while the Clark's grebe consists of a single “creeet” note, more drawn out.

Distribution and habits

Western

is home for nearly all individuals of both species of grebes. When migration occurs, the birds in the northern range will travel west in flocks, at night to the

Pacific coast Pacific coast may be used to reference any coastline that borders the Pacific Ocean. Geography Americas Countries on the western side of the Americas have a Pacific coast as their western or southwestern border, except for Panama, where the Pac ...

. Both western and Clark's grebes winter in sheltered bays or

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

on the Pacific coast and summer in freshwater lakes with marshy vegetation as well as large open areas of water. The site of nesting is usually in a shallow water

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

. Both males and females help to build a floating platform nest of vegetation (Kaufman 1996). Because of the colonial nature of these birds nests must be continually guarded during the breeding season. If left unattended other pairs of birds seeking nest sites will seize the platform. These two species, like most grebes, eat a diet consisting mostly of fish. They are also known to forage on crustaceans, insects, worms and salamanders. Foraging techniques are composed of a number of foot-propelled dives. Current research is associating the use of springing dives by the Clark's grebe, in which the bird essentially leaps from the water before submerging, allowing it to reach deeper below the surface, with possibly proving niche separation between the two species.

Reproduction

Western and Clark's grebes take part in a courtship display known as mate feeding. This occurs regularly between a mated pair during the period prior to hatching of nestlings. In both species mate feeding appears to peak shortly before egg laying and involves the male providing large quantities of food to the

begging Begging (also panhandling) is the practice of imploring others to grant a favor, often a gift of money, with little or no expectation of reciprocation. A person doing such is called a beggar or panhandler. Beggars may operate in public place ...

female. Pairs will also engage in a spectacular display, by rearing up and "rushing" across the surface of the water side by side, making a loud pattering sound with their feet. This display is not only done by mated pairs, but can also be done by two males competing for a female as well as the female along with the two males. Therefore, it has been suggested that the "rushing" ceremony is done for more than one purpose. The typical clutch size for both Western and Clark's grebes is between 2 and 4 eggs per season. They are usually a pale bluish white and become stained by the nest to a speckled brown. Downy young of the western grebe display a uniform gray along the back, a white belly along with a dark patch on the forehead. This differs in Clark's grebe where the young are almost entirely white. Both species of nestlings have an area of skin on the crown that changes color from orange to scarlet if the chick needs feeding or is in distress. Males tend to hunt and provide chicks with food more often than females, however only one fish can be caught during each dive. Fledging occurs just hours after the last nestling emerges from its shell. The semialtricial nestlings travel on the backs of their parents for several weeks, this is referred to as back brooding and both parents participate in the activity. For the first two weeks after hatching chicks are completely camouflaged by their parents back feathers and will progressively become more visible. Chicks will stay close to their parents when predators are spotted or during feedings.

References

{{Taxonbar, from=Q507184 Bird genera Podicipedidae * Taxa named by Elliott Coues