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Red-necked Grebe
Distinctive neck plumage, during breeding season
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Podicipediformes
Family:	Podicipedidae
Genus:	Podiceps
Species:	P. grisegena
Binomial name
Podiceps grisegena (Boddaert, 1783)
File:Redneckedgreberangemap.png
Breeding range   Winter range

The Red-necked Grebe, Podiceps grisegena, is a migratory, aquatic bird that breeds on shallow bodies of fresh water in northwestern North America, Europe and Asia and winters around ocean coasts or on large lakes. The bird's red neck, black cap and contrasting pale grey face make it distinctive when in breeding plumage, although it loses much of its colour in winter to appear as a nondescript dusky-grey bird. Its two subspecies are similar in plumage, and the race found in North America and eastern Asia is larger than the European form.

The Red-necked Grebe has an elaborate courtship display and a variety of loud mating calls; once paired, it builds a nest from water plants on top of floating vegetation in a shallow lake or bog. Like all grebes, it dives for fish or picks insects off vegetation, and swallows its own feathers, possibly to protect the digestive system. It is a good swimmer and diver, although its adaptations for an aquatic lifestyle make it ungainly on land. There are potential threats to this grebe from pollution and disturbance on the breeding waters, and from oil spills at sea; these have had only limited impact, and the global population is stable or growing.

Taxonomy

Grebes are small to medium-large water birds with lobed, rather than webbed, toes; there are several genera, of which the most widespread is Podiceps with nine species, one recently extinct. The Red-necked Grebe's closest relative in its genus is the fish-eating Great Crested Grebe of Europe and western Asia; it is possible that the Red-necked Grebe originally evolved in North America and later spread to Europe, where a change of diet to include more insects helped to reduce competition with its larger cousin.

The genus name Podiceps comes from Latin podicis, "vent" or "anus", and pes, "foot", and is a reference to the placement of a grebe's legs at the rear of its body. The species name grisegena is also from Latin, griseus, "grey", and gena, "cheek", and refers to the face pattern of the breeding adult.

The Red-necked Grebe has two subspecies, the nominate P. g. grisegena in Europe and western Asia, and P. g. holboelii (Holboell's Grebe, named for Danish zoologist Carl Peter Holböll) in North American and eastern Siberia. The east Asian birds have slightly smaller bills than the American form, although the differences are too small to merit separation as a third subspecies.

Description

The Red-necked Grebe is a medium-large grebe, although smaller than the Great Crested Grebe of Eurasia, and the Western and Clark's Grebes of North America. The adult of the nominate European subspecies is 40–50 cm (15.7–19.7 in) long with a 77–85 cm (30.3–33.5 in) average wingspan, and weighs 692–925 g (25–33 oz). In breeding plumage, it has a black cap extending below the eye, very pale grey cheeks and throat, a rusty red neck, dark grey back and flanks, and white underparts. The eyes are dark brown and the long, pointed bill is black with a yellow base.

The Red-necked Grebe in winter plumage is duskier than other grebes, and the dark grey cap is less defined, merging into the grey face; a pale crescent curving around the rear of the face contrasts with the rest of the head. The fore neck is whitish or light grey, the hind neck is darker grey, and the yellow of the bill is less obvious than in summer.

The sexes are similar in appearance, although the male averages heavier than the female. The chicks have a striped head and breast, and older juveniles have a striped face, diffuse blackish cap, pale red neck and extensive yellow on the bill.

The subspecies P. g. holboelii is larger than the nominate race at 43–56 cm (17–22 in) length, with a 61–88 cm (24–35 in) wingspan, and a weight of 750–1,600 g (27–57 oz). The plumages are the same as those of the nominate race, although the adult's bill is more extensively yellow. The difference in size between the sexes is greater than for this subspecies that for P. g. grisegena.

The Red-necked Grebe is unmistakeable in breeding plumage. It is less distinctive in winter, but it is larger than the fairly similar Slavonian (Horned) Grebe, with a relatively larger bill and a grey, rather than white face. It is similar in size to the Eurasian Great Crested Grebe, but that species is longer-necked, has a more contrasting head pattern, and always shows white above the eye.

The Red-necked Grebe flies with its long neck extended and its large feet trailing behind the body, giving it a stretched-out appearance. The relatively small wings are grey with white secondaries, and beat very rapidly; its small wing area means that the grebe needs a lengthy run across the water to gain the speed for take-off. Like all grebes, Red-necked is an expert swimmer; it uses its feet for propulsion underwater, and steers by rotating its legs, since its tail is too short for this purpose.

This is one of the most vocal grebes during the breeding season, but, like its relatives, it is mainly silent for the rest of the year. It has a loud, wailing or howling display call uooooh, given by a single bird or a pair in duet, by night or during the day, and often from cover. Long sequences of up to 60 consecutive notes may be delivered during singing encounters between rival territorial birds. A great variety of quacking, clucking, hissing, rattling and purring calls are also given, with much individual variation.

Distribution and habitat

The Red-necked Grebe breeds in shallow freshwater lakes, bays of larger lakes, marshes, and other inland bodies of water, often less than 3 ha (6 acres) in extent and less than 2 m (6 ft) deep. It shows a preference for waters in forested areas or, further north, in shrub tundra, and favours sites with abundant emergent vegetation, such as reedbeds. The American subspecies is less tied to a high aquatic plant density, and sometimes breeds on quite open lakes.

All populations of the Red-necked Grebe are migratory and winter mainly at sea, usually in estuaries and bays, but often well offshore where there are fish within diving reach near shallow banks or islands. The preferred passage and wintering habitat is water less than 15 m (50 ft) deep with a sand or gravel bottom, scattered rocks and patches of seaweed. During the winter, birds typically feed alone and rarely aggregate into flocks, but on migration concentrations of over 2,000 individuals may occur at favoured staging sites. Migration is usually at night, but may occur during the day, especially when over water. This is particularly noticeable in autumn on the Great Lakes, when up to 18,000 birds may pass Whitefish Point on Lake Superior; these are thought to be Canadian breeders heading for the Atlantic Ocean to winter. This easterly route is longer than that to the Pacific, but avoids the Rockies.

The breeding range of the Red-necked grebe overlaps with that of the Slavonian Grebe, although the latter species tends to be displaced from sites suited to both. The Red-necked Grebe prefers a continental temperate climate, and is less successful near coasts and in subarctic and warm temperate zones. It is usually a lowland bird, breeding below 100 m (330 ft), although has nested at up to 1800 m (5,900 ft) in Turkey.

The nominate subspecies breeds from southern Sweden and Denmark through central and eastern Europe east to western Siberia, and winters mainly in the North and Baltic Seas, with smaller numbers in the Adriatic, Black Sea, Caspian Sea, Mediterranean and on inland lakes. P. g. holboelii breeds in North America in Alaska, western and central Canada, and the northern USA east to Minnesota; in Asia it nests in eastern Siberia from Kamchatka south to Hokkaido and west to Mongolia. The Asian birds winter at sea from Japan to the East China Sea, and American breeders winter in the Pacific, mainly from southern Alaska to British Columbia (with smaller numbers south to California), and in the Atlantic from Newfoundland to Florida. Some birds remain on the Great Lakes if they are sufficiently ice-free.

Behaviour

Breeding and survival

The Red-necked Grebe usually nests as isolated pairs with more than 50 m (160 ft) between neighbouring nests, although semi-colonial nesting may occur in good sites, with up to 20 pairs each defending a linear territory. Semi-colonial breeding is more likely to occur in prime locations, such as large floating mats of vegetation with no connection to the shoreline. Such sites, safe from most predators and large enough to provide some wind and wave protection, have grebes nesting much closer to each other than shoreline breeders. Pairs nesting in these colonies produce larger clutches of eggs, which hatch earlier in the season and result in larger broods. Pairs defend their territories with various threat displays, including wing-spreading, hunching, and bill-thrusting. Breeding is often in loose association with gulls or other colonial water birds.

The monogamous pair forms in April or May on migration or at the breeding water, and a highly vocal courtship ritual commences. The elaborate breeding performance includes head-shaking, a head-lowered "cat" display, parallel rushes in an upright position and mutual presentations of green weeds, and culminates in a "penguin" dance in which pair members raise the whole body upright, breast to breast.

Like all grebes, the Red-necked Grebe nests adjacent to water, since its legs are set very far back on the body and it cannot walk well. It often breeds further within reed beds than other grebes. The nest is a floating platform of plant matter anchored to submerged or emergent vegetation, in water 0.5–0.75 m (19–29 in) deep, and with the bulk of nest below the water line. Egg-laying mainly takes place from mid-April to May in Europe, and somewhat later, from mid-May to June, in North America.

The Red-necked Grebe is normally single-brooded and lays four or five (range one to nine) dull white or pale blue eggs, which average 3.4 cm (1.4 in) in breadth, 51 cm (2.0 in) in length, and weigh about 30.5 g (1.1 oz), of which 10% is shell. Both parents take turns to incubate the eggs for 21–33 days until the precocial downy chicks hatch; they immediately climb onto the parent's back, where they spend most of their time until they are 10–17 days old. The young may be fed by the parents for up to 54 days after fledging, and can fly at 50–70 days. After breeding the adults moult their wing feathers and are temporarily flightless; migration commences once the flight feathers have regrown.

Eggs may be destroyed and chicks killed by a range of predators, including the raccoon in North America and the Carrion Crow in Europe. Pike may take swimming chicks. On average, for each adult, 0.65 young birds are still alive in August, although the mortality rate for the adult is unknown. Red-necked Grebes attempt to evade birds of prey by diving; when feeding, dives average less than 30 s, although escape dives are certainly more prolonged than that.

Feeding

On the breeding grounds, the Red-necked Grebe feeds mainly on invertebrates including adult and larval aquatic insects, such as water beetles and dragonfly larvae, crayfish and molluscs. Fish may be important locally or seasonally, especially for the American subspecies, and crustaceans can constitute up to 20% of the grebe's diet. Birds breeding at the coast often make foraging flights to inland lakes or offshore areas to feed.

Aquatic prey is obtained by diving or by swimming on surface with the head submerged, and terrestrial insects and their larvae are picked off vegetation. European breeders, which have to compete with the larger Great Crested Grebe for fish, eat a greater proportion of invertebrates than the longer-billed American subspecies, although both races eat mainly fish in winter. Birds of the nominate subspecies from the northernmost breeding populations in Finland and Russia, beyond the range of Great Crested Grebe, have a longer and more slender bill than those further south, reflecting a greater proportion of fish in the diet where their main competitor is absent. If food is short, parents may desert unhatched eggs, or allow the smallest chicks to starve, although the latter strategy appears not to be particularly efficient in protecting the older chicks.

Like other grebes, the Red-necked Grebe ingests large quantities of its own feathers, which remain in the bird's stomach. Feathers are not only swallowed by adults, mainly during self-preening, but are often fed to the young, sometimes within a day of hatching. These feathers soon decompose into a feltlike, amorphous mass, often forming a ball. The function of the feathers in the stomach is unknown, although it has been suggested that they help to protect the lower digestive tract from bones and other hard, indigestible material.

Status

The Red-necked grebe has a large range, estimated at 1–10 million square kilometres (0.4–3.8 million square miles), and a global population of 150,000–370,000 individuals, with P. g. holboellii about twice as numerous as the nominate race. The population trend has not been quantified, but it is not believed to meet the thresholds for the population decline criterion (declining more than 30% in ten years or three generations) of the IUCN Red List. For these reasons, the species is evaluated as Least Concern.

The Red-necked Grebe is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. Parties to the Agreement are required to engage in a wide range of conservation strategies which are describes in a detailed action plan. The plan is intended to address key issues such as species and habitat conservation, management of human activities, research, education, and implementation.

In North America, there are potential threats from pollutants such as polychlorinated biphenyls (PCBs) and pesticides such as DDT which cause reduced reproductive success due to egg sterility and eggshell thinning. Breeding areas may be threatened by the modification and degradation of lakes and by human disturbance from water-based recreational activities. There is no evidence to suggest that these threats could result in a significant risk to the overall population; more than 70% of North American Red-necked Grebes breed in Canada, where the population is stable or increasing. Wintering birds could be affected by future oil spills at sea, although during this season the species is widely scattered along coasts, so the effects of oil spills are likely to be small.

Notes

1. ^ Template:IUCN2006 Database entry includes justification for why this species is of least concern
2. Ogilvie & Rose (2002) 8–9
3. ^ Johnsgard (1987) 130–135
4. Ogilvie & Rose (2002) 98
5. Ogilvie & Rose (2002) 102
6. ^ Ogilvie & Rose (2002) 57–60
7. ^ Snow & Perrin (1998) 17-20
8. Sibley (2000) 29
9. ^ Snow & Perrin (1998) 20–22
10. ^ Mullarney et al 18
11. Ogilvie & Rose (2002) 92
12. ^ "Red-necked Grebe". BirdFacts. Cornell Laboratory of Ornithology. {{cite web}}: Cite has empty unknown parameter: |1= (help) Retrieved 26 August 2008
13. Fjeldsa (2004) 140
14. Johnsgard (1987) 26–36
15. Fjeldsa (2004) 10
16. ^ "BirdLife International Species factsheet: Podiceps grisegena". BirdLife International. {{cite web}}: Cite has empty unknown parameter: |1= (help) Retrieved 12 August 2008
17. ^ Harrison (1988) 217
18. Nuechterlein, Gary L. (2003). "Red-necked grebes become semicolonial when prime nesting substrate is available". The Condor. 105 (1): 80–94. {{cite journal}}: Cite has empty unknown parameter: |1= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
19. "Red-necked Grebe Podiceps grisegena (Boddaert, 1783)". Bird facts. British Trust for Ornithology. {{cite web}}: Cite has empty unknown parameter: |1= (help) Retrieved 14 August 2008
20. ^ Ogilvie & Rose (2002) 94
21. ^ "Red-necked Grebe (Podiceps grisegena)" (PDF). "Marshbird" species conservation status assessment. United States Fish and Wildlife Service. {{cite web}}: Cite has empty unknown parameter: |1= (help) Retrieved 16 August 2008
22. Chamberlin, Michael L. (1977). "Observations on the red-necked grebe nesting in Michigan" (PDF). Wilson Bulletin. 89 (1): 33&ndas, 46. {{cite journal}}: Cite has empty unknown parameters: |1=, |2=, and |coauthors= (help); Unknown parameter |month= ignored (help)
23. Fjeldsa, Jon (1982). "The adaptive significance of local variations in the bill and jaw anatomy of North European red-necked grebes Podiceps grisegena". Ornis Fennica. 59 (2–3): 84–9. {{cite journal}}: Cite has empty unknown parameters: |1=, |2=, and |3= (help)
24. Kloskowski, J. (2003). "Brood reduction in the Red-necked Grebe Podiceps grisegena". Ibis. 145 (2): 233–243. doi:10.1046/j.1474-919X.2003.00145.x. {{cite journal}}: Cite has empty unknown parameters: |1=, |2=, |3=, and |coauthors= (help); Unknown parameter |month= ignored (help)
25. Johnsgard (1987) 37–53
26. Ogilvie & Rose (2002) 96
27. "Annex 2: Waterbird species to which the Agreement applies" (PDF). Agreement on the conservation of African-Eurasian migratory Waterbirds (AEWA). UNEP/ AEWA Secretariat. {{cite web}}: Cite has empty unknown parameter: |1= (help) Retrieved 4 July 2008
28. "Introduction". African-Eurasian Waterbird Agreement. UNEP/ AEWA Secretariat. {{cite web}}: Cite has empty unknown parameter: |1= (help) Retrieved 4 July 2008

References

• Fjeldsa, Jon (2004). The Grebes: Podicipedidae. Oxford: Oxford University Press. ISBN 0198500645. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help)
• Harrison, Peter (1988). Seabirds. London: Christopher Helm. ISBN 0747014108. {{cite book}}: Cite has empty unknown parameters: |1=, |2=, and |coauthors= (help)
• Johnsgard, Paul A. (1987). Diving Birds of North America. Lincoln: University of Nebraska. ISBN 0803225660. {{cite book}}: Cite has empty unknown parameters: |1=, |2=, and |coauthors= (help)
• Mullarney, Killian (1999). Collins Bird Guide. London: HarperCollins. ISBN 0002197286. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Ogilvie, M.A. (2002). Grebes of the World. New York: Bruce Coleman Books. ISBN 1872842038. {{cite book}}: Cite has empty unknown parameters: |1= and |2= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Sibley, David (2000). The North American Bird Guide. Pica Press. ISBN 0873403984.
• Snow, David (1998). The Birds of the Western Palearctic (BWP) concise edition (2 volumes). Oxford: Oxford University Press. ISBN 019854099X. {{cite book}}: Cite has empty unknown parameter: |1= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

• USGS - Red-necked Grebe Information
• South Dakota Birds - Red-necked Grebe Information and Photos
• Flicker Field Guide Birds of the World Photographs
• Red-necked Grebe videos on the Internet Bird Collection

• IUCN Red List least concern species
• Podiceps
• Birds of Europe
• Birds of Asia
• Birds of Kazakhstan
• Birds of Saudi Arabia
• Birds of Pakistan
• Birds of Georgia (country)
• Birds of Turkey
• British Isles coastal fauna