- Spotbill
Taxobox
name = Spotbill
status = LC | status_system = IUCN3.1
status_ref = [IUCN2006|assessors=BirdLife International |year=2004|id=47189|title=Anas poecilorhyncha|downloaded=11 May 2006 Database entry includes justification for why this species is of least concern]
image_width = 204px
image_caption = A male Indian Spotbill ("A. p. poecilorhyncha")
regnum =Animal ia
phylum = Chordata
classis = Aves
ordo =Anseriformes
familia =Anatidae
genus = "Anas "
species = "A. poecilorhyncha"
binomial = "Anas poecilorhyncha"
binomial_authority = Forster, 1781
subdivision_ranks =Subspecies
subdivision =
* "A. p. poecilorhyncha" Taxobox_authority | author = Forster | date = 1781 Indian Spotbill
* "A. (p.) zonorhyncha" Taxobox_authority | author = Swinhoe | date = 1866 Chinese Spotbill
* "A. p. haringtoni" Taxobox_authority | author = (Oates | date = 1907) Burmese SpotbillThe Spotbill, "Anas poecilorhyncha", also known as the Spot-billed Duck, is a
dabbling duck which breeds in tropical and easternAsia . Thisduck is resident in the southern part of its range fromPakistan andIndia to southernJapan , but the northernsubspecies , the Chinese Spotbill ("A. p. zonorhyncha"), is migratory, wintering in southeast Asia. It is quite gregarious outside the breeding season and forms small flocks. The northernmost populations have been expanding their range northwards by more than 500 km since the early 20th century, possibly in reaction toglobal warming (Kulikova "et al." 2004).These areMallard -sized mainly grey ducks with a paler head and neck and a black bill tipped bright yellow. The wings are whitish with black flight feathers below, and from above show a white-bordered green speculum and white tertials. The male has a red spot on the base of the bill, which is absent or inconspicuous in the smaller but otherwise similar female. Juveniles are browner and duller than adults.The Chinese Spotbill is darker and browner; its body plumage is more similar to the
Pacific Black Duck . It lacks the red bill spot, and has a blue speculum.It is a bird of freshwater lakes and marshes in fairly open country and feeds by dabbling for plant food mainly in the evening or at night. It nests on the ground in vegetation near water, and lays 8-14 eggs.
Both the male and female have calls similar to the Mallard.
ystematics
The
phylogenetic placement of this species is enigmatic. The Chinese Spotbill is considered to be near the point where it might be considered a distinctspecies (e.g. Johnson & Sorenson 1999). And while molecular analyses andbiogeography indicate that most species of the mallard group in thegenus "Anas " form two distinctclade s, hybridization between all of these species is a regularly-occurring phenomenon and the hybrids are usually fully fertile. The present species is known to produce fertile hybrids with the Pacific Black Buck and thePhilippine Duck in captivity (Carboneras 1996), and naturally hybridizes with the Mallard as their ranges now overlap in thePrimorsky Krai due to the Spotbill's northward expansion (Kulikova "et al." 2004).The reason for this is that the mallard group evolved quite rapidly into lineages that differ in appearance and behavior, but are still compatible genetically. Thus, stray individuals of any one mallard group species tend to mate successfully with resident populations; this renders
mtDNA data of spurious value to determine relationships, especially as molecular studies usually have a very lowsample size .The problem with the present species lies in the fact that its position in the mallard group is ambiguous. The mallard lineages cannot be reliably separated by behavior, but only by biogeography, and it is only the
Pacific radiation in which there are species with a distinct malenuptial plumage . However, although this species, judging from its distribution, seems to belong to the Asian group, it occurs close enough to theBering Straits not to discount an originallyNorth America n origin.An initial study of mtDNA cytochrome "b" and
NADH dehydrogenase subunit 2 sequences, using one individual each of the Indian and the Chinese Spotbills, suggested that these were well distinct and that the former was a more recent divergence from the Mallard's ancestors, and both being solidly nested within the Pacific clade (Johnson & Sorenson 1999).But another study (Kulikova "et al." 2004), utilizing a good sample of Chinese Spotbill and Mallard specimens from the area of contact, and analyzing mtDNA
control region andornithine decarboxylase intron 6 sequence data, found "A. (p.) zonorhyncha" to be more closely related to the American clade, which contains such species as the Mottled andAmerican Black Duck s. It further revealed that, contrary to what was initially believed, female Spot-billed Ducks do not seem to prefer the brightly-colored Mallard drakes to their own species' males, with hybrids being more often than not between Spotbill drakes and Mallard hens, but this might simply be due to the more strongly vagrant drakes being over-represented in the northwards-expanding population.In conclusion, it seems clear that Johnson & Sorenson's 1999 study cannot be relied upon: the perceived relationships as presented there are far more likely than not due to the small sample size. But the apparent similarities to the American species are also misleading: thorough analysis of mtDNA control region
haplotype s (Kulikova "et al." 2004, 2005) concluded that the similarities between the Spotbill and the American "mallardines" were due toconvergent evolution on the molecular level. Rather than being derived from the North American clade, the spotbill seems to hold a phylogenetic position close to the point where the Pacific and American lineages separated, evolving independently from there except for occasional hybridization events with the Mallard, although the relationships of "zonorhyncha" to the Pacific Black Duck deserve further study.Trivia
In the Japanese manga and anime "
One Piece ", there is a "Super Spotbill" named Karoo which is owned byNefertari Vivi . Also, the characterFarfetch'd in thePokémon series is based on the spotbill.Gallery
References
Bibliography
* Carboneras, Carles (1992): 87. Spot-billed Duck. "In:" del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (editors): "
Handbook of Birds of the World , Volume 1: Ostrich to Ducks": 607, plate 46. Lynx Edicions, Barcelona. ISBN 84-87334-10-5* Johnson, Kevin P. & Sorenson, Michael D. (1999): Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence. "Auk" 116(3): 792–805. [http://elibrary.unm.edu/sora/Auk/v116n03/p0792-p0805.pdf PDF fulltext]
* Kulikova, Irina V.; Zhuravlev, Yury N. & McCracken, Kevin G. (2004): Asymmetric hybridization and sex-biased gene flow between Eastern Spot-billed Ducks ("Anas zonorhyncha") and Mallards ("A. platyrhynchos") in the Russian Far East. "Auk" 121(3): 930-949. [English with Russian abstract] DOI: 10.1642/0004-8038(2004)121 [0930:AHASGF] 2.0.CO;2 [http://mercury.bio.uaf.edu/~kevin_mccracken/reprints/auk-121-930.pdf PDF fulltext]
* Kulikova, Irina V.; Drovetski, S. V.; Gibson, D. D.; Harrigan, R. J.; Rohwer, S.; Sorenson, Michael D.; Winker, K.; Zhuravlev, Yury N. & McCracken, Kevin G. (2005): Phylogeography of the Mallard ("Anas platyrhynchos"): Hybridization, dispersal, and lineage sorting contribute to complex geographic structure. "Auk" 122(3): 949-965. [English with Russian abstract] DOI: 10.1642/0004-8038(2005)122 [0949:POTMAP] 2.0.CO;2 [http://mercury.bio.uaf.edu/~kevin_mccracken/reprints/auk-122-949.pdf PDF fulltext] Erratum: "Auk" 122(4): 1309. DOI: 10.1642/0004-8038(2005)122 [0949:POTMAP] 2.0.CO;2
Wikimedia Foundation. 2010.