Black-necked grebe

The black-necked grebe or eared grebe (Podiceps nigricollis) is a member of the grebe family of water birds. It was described in 1831 by Christian Ludwig Brehm. Its breeding plumage features distinctive ochre-coloured feathers which extend behind its eye and over its ear coverts. The rest of the upper parts, including the head, neck, and breast, are coloured black to blackish brown. The flanks are tawny rufous to maroon-chestnut, and the abdomen is white. In its non-breeding plumage, this bird has greyish-black upper parts, including the top of the head and a vertical stripe on the back of the neck. The flanks are also greyish-black. The rest of the body is a white or whitish colour. The juvenile has more brown in its darker areas. This species is present in parts of Africa, Eurasia, and the Americas.

The black-necked grebe uses multiple foraging techniques. Insects, which make up the majority of this bird's diet, are caught either on the surface of the water or when they are in flight; this species occasionally practices foliage gleaning. This grebe dives to catch crustaceans, molluscs, tadpoles, and small frogs and fish. When moulting at saline lakes, this bird feeds mostly on brine shrimps(such as Artemia franciscana, and "Artemia parthenogenetica"). in 1831, who gave this bird its current scientific name of Podiceps nigricollis from a German bird. To resolve this, the International Commission on Zoological Nomenclature suppressed the name Colymbus caspicus.

Subspecies

There are currently three accepted subspecies.

{| class="wikitable "

! Summer !! Winter !! Scientific name !! Common name !! Distribution !! Notes

|120px Altlußheim, Baden-Württemberg, Germany || 120px Borith Lake, Gilgit-Baltistan, Pakistan || P. n. nigricollis Brehm, 1831 || Black-necked grebe (Eurasian) || Across the temperate Palearctic from western Europe to eastern Asia, wintering further south to northern Africa, the Persian Gulf, and southern China. as well as by photographic evidence.

|120px Tule Lake NWR, Klamath Basin, California, USA || 120px San Luis Obispo, California, USA || P. n. californicus (Heermann, 1854) || Eared grebe || Interior southwestern Canada and the western United States, wintering on the Pacific coast and inland waters from southwestern Canada south to Guatemala, || Longer bill than other the subspecies.

Etymology

The generic name, Podiceps, comes from two Latin words: , meaning or , and meaning . This is a reference to the attachment point of the bird's legs at the extreme back end of its body. The specific epithet nigricollis is Latin for : means and means . The subspecies epithet californicus comes from "California", while gurneyi comes from the name of British ornithologist John Henry Gurney Sr.

"Black-necked grebe" has been designated the official name by the International Ornithological Committee (IOC). Both common names for this species refer to features visible when the bird is in its breeding plumage; in such plumage, it has an all-black neck and a spray of golden plumes on each side of its head. The name "eared grebe" is nearly a century older than the name "black-necked grebe". The latter was first used in 1912 by Ernst Hartert, in an effort to bring the common name of the species in line with its scientific name, and/or to avoid the long history of confusion between the vernacular name "eared" with the scientific name of the horned grebe Podiceps auritus (auritus, Latin, 'eared'). The name "eared grebe" is still used in North America to refer to this bird. and in P. n. californicus. It weighs , with males being on average heavier than females. The thin, upturned bill, on the other hand, is black, and is connected to the eye by a blackish line starting at the . Sometimes, the foreneck can be found to be mostly tinged brown. The is blackish to drab brown in colour and has a white patch formed by the secondaries and part of the inner primaries. The flanks are coloured tawny rufous to maroon-chestnut and have the occasional blackish fleck. The and abdomen is white, with an exception to the former being the dark tertials and the mostly pale grey-brown outer primaries. The legs are a dark greenish grey. The sexes are similar. Then, after completing the moult and waiting for sometimes several months, although larger wintering populations there are mainly restricted to islands in the Gulf of California, the Salton Sea, and Baja California. When not breeding, its habitat is primarily saline lakes, sheltered inshore seas, and coastal estuaries.

Breeding

This species builds its floating nest in the usually shallow water of open lakes. The nest itself is anchored to the lake by plants. It is built by both the male and the female and made out of plant matter. and by itself. When it does not nest by itself, it will often nest in mixed-species colonies made up of black-headed gulls, ducks, and various other waterbirds.

thumb|left|Eared grebes courting, Tule Lake NWR, Klamath Basin, California|alt=Two eared grebes in an upright posture in the water.

Pair formation in the black-necked grebe usually starts during pauses in the migration to the breeding grounds, although it occasionally occurs before, in wintering pairs. This pair formation continues after this grebe has arrived to its breeding grounds. Courtship occurs when it arrives at the breeding lake. The displays are performed in the middle of the lake. There is no territory involved in courting; individuals use the whole area of the lake. When advertising for a mate, a black-necked grebe will approach others of its species with its body fluffed out and its neck erect. It closes its beak to perform a call, poo-eee-chk, with the last note only barely audible. Courtship generally stops at the start of nesting.

In the Northern Hemisphere, this bird breeds from April to August. In east Africa, the breeding season is at least from January to February, while in southern Africa, the breeding season is from October to April. In terms of territory, this grebe will defend only its nest site. This behaviour is present in all grebes, and is likely to have evolved because it reduces travel costs, specifically those back to the nest to brood the chicks and give them food. After about 10 days, the parents split the chicks up, with each parent taking care of about half of the brood. Predation is usually not the primary cause of egg loss, with most nesting failures occurring after the chicks have hatched. A major cause of this is the chilling of the young. In between dives, this grebe rests for an average of 15 seconds. When feeding on brine shrimp at hypersaline lakes, it likely uses its large tongue to block the oral cavity. It is suggested that it then crushes prey against its palate to remove excess water. It also forages by gleaning foliage, plucking objects off of the surface of water, having its head submerged while swimming, and sometimes capturing flying insects.

The young are fed one at a time by the parents, with one bird carrying the young while the other feeds it. The young take food by grabbing it, with their beaks, from their parents, or by grabbing food dropped into the water. When a young bird cannot grab the food, then the adults submerge their bill into the water and shake their bill to break up the food. This migration is to saline lakes, especially lakes with large numbers of invertebrate prey, so that birds can fatten up while moulting before continuing on the winter migration. The moult migration is dangerous, with hundreds and sometimes thousands of birds being killed by snowstorms when traveling to places such as Mono Lake.

After the moult migration, birds moult their remiges between August and September, which makes them unable to fly. The moult is preceded by an increase in weight. During the moult, the breast muscles atrophy. When the moult is completed, birds continue to gain weight, often more than doubling their original weight. Migration usually starts earlier when shrimps are more abundant and when the moulting lake is at a higher than average temperature. Birds generally leave on a clear night with lower than average surface temperatures.

Movement

thumb|Diving|alt=The backside of a bird that is diving into water.

This grebe is one of the most inefficient fliers among birds. Generally, it avoids flying at all costs and reserves long-distance flight exclusively for migration. In flight, the shape of this grebe is like a loon: straight neck, legs trailing, and wings beating often. The cause of the outbreak and modes of transmission are unknown, but there has been speculation about the latter. Since West Nile virus is able to survive in brine shrimps (and, for a temporary time, water at specific temperatures), it is likely that grebes could have become infected by eating diseased shrimps and/or swimming in the contaminated water. It is also suggested that West Nile virus could be transmitted among grebes through contact with the excrement of an infected bird, possibly around bodies of water, communal nest sites, areas of cohabitating birds, etc. Large-scale disease, such as avian cholera, could threaten the species. These and other factors, such as human disturbance, including collisions with power transmission lines, contribute to declining populations in certain areas. This species used to be threatened in North America by the millinery industry, which helped facilitate the hunting of the birds, and egg collectors. Although this is true, this grebe is hunted in the Gilan Province in Iran, for both commercial and recreational purposes. However, there is no evidence suggesting that these threats could result in a significant risk for the overall population.