Western grebe
Western grebe | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Podicipediformes |
Family: | Podicipedidae |
Genus: | Aechmophorus |
Species: | A. occidentalis
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Binomial name | |
Aechmophorus occidentalis (Lawrence, 1858)
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Approximate distribution map
Breeding
Migration
Year-round
Nonbreeding
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Synonyms | |
The western grebe[2] (Aechmophorus occidentalis)[3] is a species in the grebe family of water birds. Folk names include "dabchick", "swan grebe" and "swan-necked grebe".
Western grebe fossils from the
Description
The western grebe is the largest North American grebe. It is 55–75 cm (22–30 in) long, weighs 795–2,000 g (1.753–4.409 lb) and measures 79–102 cm (31–40 in) across the wings.[8][9][10] It is black-and-white, with a long, slender, swan-like neck and red eyes. It is easily confused with Clark's grebe, which shares similar features, body size, behavior and habitat, and hybrids are known. Western grebes nest in colonies on lakes that are mixed with marsh vegetation and open water. Western Grebe nests are made of plant debris and sodden materials, and the nest-building begins roughly around late April through June. The construction is done by both sexes and is continued on throughout laying and incubation.[11] This species of waterbirds is widespread in western North America, so there is no specific place of abundance. Its subspecies, Clark's grebe generally populate more of the southern part of North America [12] Other differences are whiter flanks and paler gray backs when comparing A.o.clarkii to A.o.occidentalis.[13] The western grebe has black around the eyes and a straight greenish-yellow bill whereas the Clark's grebe has white around the eyes and an up-turned bright yellow bill. The downy young of Western are grey; Clark's downy young are white.
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Out of the water
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Swimming
Subspecies
In 1858
- A. occidentalis ssp. occidentalis, (Lawrence, 1858), large, dark morph, from western Canada & United States (California, Utah)
- A. occidentalis ssp. ephemeralis, Dickerman, 1986 - Smaller than the western grebe, dark morph, from north & central Mexico.
- A. clarkii ssp. clarkii, (Lawrence, 1858) Dickerman, 1963 - Small, pale morph, from north & central Mexico
- A. clarkii ssp. transitionalis, Dickerman, 1986, large, pale morph, from western Canada & United States (California, Utah)
Multiple lines of evidence suggest that the differently colored western grebes (darker and lighter) are different taxa -in a single population in which sympatric speciation somehow persists. These forms were reported to mate according to their own colors and the mixing between dark and light-faced individuals is rare.[13] This type of assortative mating derives from possible isolating mechanisms such as differential responses to advertising calls and spatial distribution.[13][16] Each of the forms tended to stay closer to their own type, thus making their colony nesting be non-randomly distributed.[13]
By 1992 Storer & Nuechterlein were promoting another concept to the taxon A. clarkii, now regarding the pale morphs from the US and Canada to be this taxon (Dickerman's A. occidentalis ssp. ephemeralis).[17]
Breeding
Western grebes nest in colonies of hundreds on large inland
Communication style
When tending their young, Western grebe parents use different types of vocalization to communicate. Ticking is one of the two and is used as an alarm signal. Parents carry their newly hatched young on their backs, and when the parents make a ticking sound, this is used as a signal for their chicks to hide their heads beneath the back of their parents and be silent. If chicks are greater than 4 weeks of age, they respond to the ticking by swimming or diving away on their own. When making a ticking sound, the callers do not open their mouths, so it is hard to distinguish who is the maker of the sound. The parent who carries the chicks tend to make the ticking sound more often than those that do not, and both of male and female parents are equally likely to tick. Another vocalization noise is clucking, and this signals for food. When a parent clucks, the young respond to it by poking their head out of their parent back where they are on to receive food.[21]
Reproduction and survival
The clutch size decreases as the mating season progresses, meaning if the mating is done at the last of days in mating season, the number of offspring produced is smaller.[22] However it is also stated brood size of nests that hatched later in the season is larger than those from earlier, which contradicts previous findings.[22] This may be due to ecological constraints. Ecological constraints also pressure the young, and this may lead to siblicide in the first weeks after hatching, which may explain the brooding differences.[22] Also, Western grebes are sensitive to humans, such that when there is human disturbance near them, the parents leave their nest, leaving their unhatched eggs vulnerable to attacks by predators. This shows the predation or even the seemingly threatening acts result in a decrease of reproduction and survival of the young.[23] Because they are so sensitive, there have been restoration efforts to rebuild the Western grebes' native habitats, so that they have greater opportunity to reproduce and raise their young without disturbance or threat. The number of Grebes has been slowly declining in the last two decades, not only because of predation, but also because of habitat destruction, with oil spillage being one of the major causes.[24]
Food and feeding
This bird dives for
References
- . Retrieved 12 November 2021.
- ^ "Western Grebe". Birds of North America. Cornell Lab of Ornothology. Retrieved 7 April 2017.
- ^ Etymology: Aechmophorus, "spear-bearer", from Ancient Greek aichme (a spear) + phoros (one who bears something around), in reference to its bill; occidentalis: Latin for "western".
- ^ Miller, Loye H. (1911). "Additions to the avifauna of the Pleistocene deposits at Fossil Lake, Oregon". University of California Publications, Bulletin of the Department of Geology. 6: 79–87.
- Howard, Hildegarde(1946). "A review of the Pleistocene birds of Fossil Lake, Oregon". Carnegie Institution of Washington Publications. 551: 141–195.
- JSTOR 1366369.
- ^ Storer, Robert W. (1989). "The Pleistocene Western Grebe Aechmophorus (Aves, Podicipedidae) from Fossil Lake, Oregon: A comparison with Recent material" (PDF). Contributions from the Museum of Paleontology, University of Michigan. 27 (12): 321–326.
- ^ Western Grebe. All About Birds
- ISBN 978-0-8493-4258-5.
- ISBN 0789477645
- ISSN 1524-4695
- ^ Kenn, Kaufman (2007)., Western Grebe. Birder's World, 21(6), 40-42.
- ^ a b c d Ratti, J. T. (1979). Reproductive Separation and Isolating Mechanisms between Sympatric Dark- and Light- Phase Western Grebes. American Ornithological Society, 93(3), 573-586.
- ^ Ratti, John T. (July 1979). "Reproductive Separation and Isolating Mechanisms Between Sympatric Dark- and Light-phase Western Grebes" (PDF). The Auk. 96: 573–586. Retrieved 25 November 2018.
- ^ Dickerman, Robert W. (1986). "Two Hitherto Unnamed Populations Of Aechmophorus (Aves: Podicipitidae)". Proceedings of the Biological Society of Washington. 99: 435–436. Retrieved 25 November 2018.
- ^ Storer, R. W., & Nuechterlein, G. L. (1985). Analysis Of Plumage and Morphological Characters of the Two Color Forms of the Western Grebe (Aechmophorus). American Ornithological Society, 102(1), 102-119.
- doi:10.2173/bna.26b. Retrieved 7 April 2017.
- ^ a b Nuechterlein, G. L., & Storer, R. W. (1982). The Pair-Formation Displays of the Western Grebe. American Ornithological Society, 84(4), 351-369.
- ^ a b Lindsay, S. (2007, September 8). Elegant Western Grebes; Elaborate Mating Rituals Evoke Thoughts of Dance. The Spokesman-Review, pp. 8
- ^ Nuechterlein, G. L., & Storer, R. W. (1989). Mate Feeding by Western and Clark's Grebes. American Ornithological Society, 91(1), 37-42.
- ^ Nuechterlein, G. L. (1988). Parent-Young Vocal Communication in Western Grebes. American Ornithological Society, 90(3), 632-636.
- ^ a b c Robison, K. M., Anderson, D. W., & Robison, R. E. (2014). Brood Size and Nesting Phenology in Western Grebe (Aechmophorus occidentalis) and Clark's Grebe (Aechmophorus clarkii) in Northern California. BioOne, 38(1), 99-105.
- ^ Seattle Audubon Society (n.d.). Western Grebe. Retrieved from [1].
- ^ Mills, K. L., Gaydos, J. K., Fiorello, C. V., Whitmer, E. R., De La Cruz, S., Mulcahy, D. M., … Ziccardi, M. H. (2015). Post-Release Survival and Movement of Western Grebes (Aechmophorus occidentalis) Implanted with Intracoelomic Satellite Transmitters. Waterbirds, 39(2), 175-186.
- S2CID 88653499.
Further reading
- Nuechterlein, Gary L. (May 1982). "The Birds That Walk on Water". OCLC 643483454.
External links
- Western Grebe Species Account - Cornell Lab of Ornithology
- Western Grebe - Aechmophorus occidentalis - USGS Patuxent Bird Identification InfoCenter
- Stamps[usurped] (for Canada) at bird-stamps.org
- "Aechmophorus occidentalis". Integrated Taxonomic Information System. Retrieved 24 February 2009.
- "Western Grebe media". Internet Bird Collection.
- Western Grebe photo gallery at VIREO (Drexel University)