Spotbill
Encyclopedia
The Spot-billed Duck also known as the Spotbill, is a dabbling duck which breeds in tropical and eastern Asia
. It has three subspecies: the Indian Spot-billed Duck (A. poecilorhyncha poecilorhyncha), Eastern Spot-billed Duck (A. poecilorhyncha zonorhyncha), and Burmese Spot-billed Duck (A. poecilorhyncha haringtoni).
This duck
is resident in the southern part of its range from Pakistan
and India
to southern Japan
, but the northern subspecies
, the Eastern Spot-billed Duck (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 expanded their range northwards by more than 500 km since the early 20th century, possibly in reaction to global warming
.
This duck is around the same size as a Mallard
. It measures 55–63 cm (21.7–24.8 in) in length and 83–95 cm (32.7–37.4 in) across the wings, with a body mass of 790–1500 g (1.7–3.3 lb). These are 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 Eastern Spot-billed Duck 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 lake
s and marsh
es 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
.
The phylogenetic placement of this species is enigmatic. The Eastern Spotbill is often considered a distinct species by many taxonomists. (e.g. Johnson & Sorenson 1999). And while molecular analyses and biogeography
indicate that most species of the mallard group in the genus
Anas
form two distinct clade
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 Duck and the Philippine Duck
in captivity, and naturally hybridizes with the Mallard as their ranges now overlap in the Primorsky Krai
due to the Spotbill's northward expansion.
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 low sample 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 male nuptial plumage. However, although this species, judging from its distribution, seems to belong to the Asian group, it occurs close enough to the Bering Straits not to discount an originally North America
n origin.
An initial study of mtDNA cytochrome b
and NADH dehydrogenase
subunit
2 sequence
s, using one individual each of the Indian and the Eastern Spot-billed Ducks, 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.
But another study, utilizing a good sample of Eastern Spot-billed Duck and Mallard specimens from the area of contact, and analyzing mtDNA control region and ornithine 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
and American 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 Spot-billed Duck 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 concluded that the similarities between the Spot-billed Duck and the American "mallardines" were due to convergent 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.
, there is a "Super Spot-billed Duck" named Karoo which is owned by Nefertari Vivi. Also, the Farfetch'd
species in the Pokémon
series is possibly based on the spot-billed duck. In Super Mario World 2: Yoshi's Island the character Huffin' Puffins' Japanese name "karugamo" corresponds to the name of the Anas poecilorhyncha.
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. It has three subspecies: the Indian Spot-billed Duck (A. poecilorhyncha poecilorhyncha), Eastern Spot-billed Duck (A. poecilorhyncha zonorhyncha), and Burmese Spot-billed Duck (A. poecilorhyncha haringtoni).
This duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
is resident in the southern part of its range from Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
to southern Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, but the northern subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, the Eastern Spot-billed Duck (A. p. zonorhyncha), is migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, wintering in Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
. It is quite gregarious outside the breeding season and forms small flocks. The northernmost populations have expanded their range northwards by more than 500 km since the early 20th century, possibly in reaction to global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
.
This duck is around the same size as a Mallard
Mallard
The Mallard , or Wild Duck , is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand and Australia....
. It measures 55–63 cm (21.7–24.8 in) in length and 83–95 cm (32.7–37.4 in) across the wings, with a body mass of 790–1500 g (1.7–3.3 lb). These are mainly grey ducks with a paler head and neck and a black bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
tipped bright yellow. The wings are whitish with black flight feathers below, and from above show a white-bordered green speculum
Speculum feathers
The speculum is a patch, often distinctly coloured, on the inner remiges of some birds.Examples of the colour of the speculum in a number of ducks are:* Common Teal and Green-winged Teal: Iridescent green edged with buff....
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 Eastern Spot-billed Duck is darker and browner; its body plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
is more similar to the Pacific Black Duck
Pacific Black Duck
The Pacific Black Duck is a dabbling duck found in much of Indonesia, New Guinea, Australia, New Zealand, and many islands in the southwestern Pacific, reaching to the Caroline Islands in the north and French Polynesia in the east. It is usually called the Grey Duck in New Zealand...
. It lacks the red bill spot, and has a blue speculum.
It is a bird of freshwater lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
s and marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
es 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
Bird egg
Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one to about 17...
.
Both the male and female have calls similar to the Mallard
Mallard
The Mallard , or Wild Duck , is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand and Australia....
.
Systematics
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
indicate that most species of the mallard group in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Anas
Anas
Anas is a genus of dabbling ducks. It includes mallards, wigeons, teals, pintails and shovelers in a number of subgenera. Some authorities prefer to elevate the subgenera to genus rank...
form two distinct clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
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 Duck and the Philippine Duck
Philippine Duck
The Philippine Duck is a large dabbling duck of the genus Anas. It is endemic to the Philippines. As few as 5,000 may remain. Overhunting and habitat loss has contributed to its decline....
in captivity, and naturally hybridizes with the Mallard as their ranges now overlap in the Primorsky Krai
Primorsky Krai
Primorsky Krai , informally known as Primorye , is a federal subject of Russia . Primorsky means "maritime" in Russian, hence the region is sometimes referred to as Maritime Province or Maritime Territory. Its administrative center is in the city of Vladivostok...
due to the Spotbill's northward expansion.
The reason for this is that the mallard group evolved
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
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 low sample size
Sample size
Sample size determination is the act of choosing the number of observations to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make inferences about a population from a sample...
.
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 male nuptial plumage. However, although this species, judging from its distribution, seems to belong to the Asian group, it occurs close enough to the Bering Straits not to discount an originally North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n origin.
An initial study of mtDNA cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
and NADH dehydrogenase
NADH dehydrogenase
NADH dehydrogenase is an enzyme located in the inner mitochondrial membrane that catalyzes the transfer of electrons from NADH to coenzyme Q...
subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
2 sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s, using one individual each of the Indian and the Eastern Spot-billed Ducks, 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.
But another study, utilizing a good sample of Eastern Spot-billed Duck and Mallard specimens from the area of contact, and analyzing mtDNA control region and ornithine decarboxylase
Ornithine decarboxylase
The enzyme ornithine decarboxylase catalyzes the decarboxylation of ornithine to form putrescine. This reaction is the committed step in polyamine synthesis. In humans, this protein has 461 amino acids and forms a homodimer....
intron
Intron
An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...
6 sequence data, found A. (p.) zonorhyncha to be more closely related to the American clade, which contains such species as the Mottled
Mottled Duck
The Mottled Duck or Mottled Mallard is a medium-sized dabbling duck. It is intermediate in appearance between the female Mallard and the American Black Duck. It is closely related to those species, and is sometimes considered a subspecies of the former, but this is inappropriate .There are two...
and American Black Duck
American Black Duck
The American Black Duck is a large dabbling duck. American Black Ducks are similar to Mallards in size, and resemble the female Mallard in coloration, although the Black Duck's plumage is darker...
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 Spot-billed Duck 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
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
s concluded that the similarities between the Spot-billed Duck and the American "mallardines" were due to convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
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 PieceOne Piece
is a Japanese shōnen manga series written and illustrated by Eiichiro Oda. It has been serialized in Weekly Shōnen Jump since August 4, 1997; the individual chapters are being published in tankōbon volumes by Shueisha, with the first released on December 24, 1997, and the 64th volume released as...
, there is a "Super Spot-billed Duck" named Karoo which is owned by Nefertari Vivi. Also, the Farfetch'd
Farfetch'd
Farfetch'd, known in Japan as , is a Pokémon species in Nintendo and Game Freak's Pokémon franchise. Created by Ken Sugimori, Farfetch'd first appeared in the video games Pokémon Red and Blue and subsequent sequels, later appearing in various merchandise, spinoff titles and animated and printed...
species in the Pokémon
Pokémon
is a media franchise published and owned by the video game company Nintendo and created by Satoshi Tajiri in 1996. Originally released as a pair of interlinkable Game Boy role-playing video games developed by Game Freak, Pokémon has since become the second most successful and lucrative video...
series is possibly based on the spot-billed duck. In Super Mario World 2: Yoshi's Island the character Huffin' Puffins' Japanese name "karugamo" corresponds to the name of the Anas poecilorhyncha.