Chinese Merganser
Encyclopedia
The Scaly-sided Merganser or Chinese Merganser (Mergus squamatus) is an endangered typical merganser
(genus
Mergus). It lives in temperate
East Asia
, breeding in the north and wintering in the south.
dark brown in both sexes.
, perhaps in North Korea
, and in northeastern China
. The bulk of the species
' population seems to breed in the Xiao Xingangling Mountains (Heilongjiang Province) and Changbai Mountains
of China. M. squamatus are migratory
, wintering in central and southern China, with small numbers in Japan
, South Korea
, Taiwan
, northern Vietnam
, Myanmar
and Thailand
. They arrive on the breeding grounds as soon as winter is over, in March, and leave when the first cold nights come in late October.
This shy and easily startled bird favors mid-sized rivers which meander
through wide expanses of mixed forest in the lowlands, up to 1,000 meters ASL
or less. Birds tend to move upriver during the day, both when startled and when foraging; the latter is probably because stirred-up sediment
s will alert and hide prey downstream. Food is caught with the serrated beak from among the riverbed
gravel
. Often the birds dive for prey, repeatedly submerging for a quarter-to half-minute with only a few seconds pause between dives. In shallow water, the birds submerge only the head; they do not upend
. The birds are not very social, and only rarely encountered in groups larger than pairs or families. Even on the wintering grounds, groups of more than a dozen are very rare.
They spend most of the daylight time foraging, except around noon when they take some time to rest, preen
and socialize at the river banks, where they also sleep. The food of M. squamatus consists of aquatic
arthropod
s and small or young fish
. Stonefly (Plecoptera) and Phryganeidae giant caddisfly larva
e may constitute the bulk of its diet when available. Beetle
s and crustacean
s are eaten less regularly, though the latter may be more important in autumn. As aquatic insect larvae hatch in the course of the summer, fish become more prominent in the diet. Favorite fish species include the Dojo Loach (Misgurnus anguillicaudatus) and the lenok Brachymystax lenok
. More rarely eaten are such species as the lamprey
Eudontomyzon morii, the sculpin
Mesocottus haitej, or the Arctic Grayling
(Thymallus arcticus). Thus, they are opportunistic feeders; regarding fish, they will probably eat any species that has the correct elongated shape and small size.
Scaly-sided Mergansers nest in tree
s, as typical for the merganser and goldeneye
lineage of sea ducks. Preferred nesting trees are such species as Daimyo Oak
(Quercus dentata) and Ussuri Poplar (Populus ussuriensis, 大青杨; a balsam poplar
).
They are sympatric with Mandarin Duck
s (Aix galericulata); though both relish the same insect larvae, they do not seem to compete for food, but perhaps for nesting holes (which neither can excavate themselves). In its winter quarters, the Scaly-sided Merganser might compete with other Merginae
with which it shares its habitat then, e.g. Common Merganser
s (M. merganser) and Common Goldeneye
s (Bucephala clangula).
is considered endangered
by the IUCN. Its numbers declined in the 1960s and 1970s due to loss of primary forests in its limited range, particularly along the major rivers. Current threats include illegal hunting, entanglement in fishing nets and river pollution
, as well as ongoing destruction of forest. According to its current IUCN classification EN C2a(ii), fewer than 2500 adult birds remain, and most of these are found in the region where the borders of China
, North Korea
and Russia
meet.
A confounding factor is that the Scaly-sided Merganser is rather solitary and extremely shy and alert. Thus, even though its range is still quite extensive, an accurate estimate of its population is difficult. A somewhat crude but nonetheless important indication of the Scaly-sided Merganser's population status may be gleaned by annual censuses on the lower Yangtze River
, which constitutes the single most important wintering area known to date. The mid-2000s assumption of a 20% or more decline in numbers til 2010 is discarded at present, because though the decline is certainly ongoing there is still too little data to quantify it that accurately.
Mergus
Mergus is the genus of the typical mergansers, fish-eating ducks in the seaduck subfamily . The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related...
(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...
Mergus). It lives in temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
East Asia
East Asia
East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...
, breeding in the north and wintering in the south.
Description
This striking sea duck has a thin red bill and a scaled dark pattern on the flanks and rump. Both sexes have a crest of wispy elongated feathers, reaching almost to the shoulders in adult males and being fairly short in females and immatures. The adult male has a black head and neck, white breast and underparts, and blackish mantle and wings, except for the white innerwings. The scaling is also black, while the tail is medium grey. The female has a buffish head and otherwise replaces the male's black with grey colour. The legs are orange-red and the iridesIris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
dark brown in both sexes.
Ecology
Their breeding habitat is rivers in primary forest in the southeastern Russian Far EastRussian Far East
Russian Far East is a term that refers to the Russian part of the Far East, i.e., extreme east parts of Russia, between Lake Baikal in Eastern Siberia and the Pacific Ocean...
, perhaps in North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...
, and in northeastern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. The bulk of the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
' population seems to breed in the Xiao Xingangling Mountains (Heilongjiang Province) and Changbai Mountains
Changbai Mountains
The Changbai Mountain Range or Jangbaek Mountain Range are a mountain range on the border between China and North Korea...
of China. M. squamatus are 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 central and southern China, with small numbers in 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...
, South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, northern Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
, Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....
and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. They arrive on the breeding grounds as soon as winter is over, in March, and leave when the first cold nights come in late October.
This shy and easily startled bird favors mid-sized rivers which meander
Meander
A meander in general is a bend in a sinuous watercourse. A meander is formed when the moving water in a stream erodes the outer banks and widens its valley. A stream of any volume may assume a meandering course, alternately eroding sediments from the outside of a bend and depositing them on the...
through wide expanses of mixed forest in the lowlands, up to 1,000 meters ASL
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...
or less. Birds tend to move upriver during the day, both when startled and when foraging; the latter is probably because stirred-up sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s will alert and hide prey downstream. Food is caught with the serrated beak from among the riverbed
Riverbed
Riverbed may refer to:*Stream bed, the channel bottom of a stream or river or creek*Wadi, a dry riverbed that contains water only during times of heavy rain*Riverbed Technology, an American technology company...
gravel
Gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...
. Often the birds dive for prey, repeatedly submerging for a quarter-to half-minute with only a few seconds pause between dives. In shallow water, the birds submerge only the head; they do not upend
Upend
Upend is a village in the east of the English county of Cambridgeshire....
. The birds are not very social, and only rarely encountered in groups larger than pairs or families. Even on the wintering grounds, groups of more than a dozen are very rare.
They spend most of the daylight time foraging, except around noon when they take some time to rest, preen
Preen
- Birds :*Preen, personal grooming of a bird's feathers especially by using its beak*Preen gland, also called the uropygial gland, an oil gland found in many bird species*Preen oil, an oil made by the uropygial gland found in many bird species...
and socialize at the river banks, where they also sleep. The food of M. squamatus consists of aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s and small or young fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. Stonefly (Plecoptera) and Phryganeidae giant caddisfly larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e may constitute the bulk of its diet when available. Beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s are eaten less regularly, though the latter may be more important in autumn. As aquatic insect larvae hatch in the course of the summer, fish become more prominent in the diet. Favorite fish species include the Dojo Loach (Misgurnus anguillicaudatus) and the lenok Brachymystax lenok
Brachymystax lenok
Brachymystax lenok is a salmonid fish distributed throughout Siberia, Korea and North China. It is an economically important fish species but now on the verge of extinction due to overexploitation and environmental pollution....
. More rarely eaten are such species as the lamprey
Lamprey
Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...
Eudontomyzon morii, the sculpin
Sculpin
A Sculpin is a fish that belongs to the order Scorpaeniformes, suborder Cottoidei and superfamily Cottoidea, that contains 11 families, 149 genera, and 756 species...
Mesocottus haitej, or the Arctic Grayling
Arctic grayling
Arctic grayling is a species of freshwater fish in the salmon family of order Salmoniformes. It comprises five subspecies native to the Nearctic and Palearctic ecozones. T. a. arcticus is widespread throughout the Arctic and Pacific drainages in Canada, Alaska, and Siberia, as well as the upper...
(Thymallus arcticus). Thus, they are opportunistic feeders; regarding fish, they will probably eat any species that has the correct elongated shape and small size.
Scaly-sided Mergansers nest in tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, as typical for the merganser and goldeneye
Goldeneye (duck)
Goldeneye are small tree-hole nesting northern hemisphere seaducks belonging to the genus Bucephala. Their plumage is black and white, and they eat fish, crustaceans and other marine life....
lineage of sea ducks. Preferred nesting trees are such species as Daimyo Oak
Daimyo Oak
Quercus dentata, the Daimyo Oak is a species of oak native to Japan, Korea and China.It is a deciduous tree growing up to 20-25 m tall, with a trunk up to 1 m diameter...
(Quercus dentata) and Ussuri Poplar (Populus ussuriensis, 大青杨; a balsam poplar
Balsam poplar
The balsam poplars — also known as Populus sect. Tacamahaca — are a group of about 10 species of poplars, indigenous to North America and eastern Asia, distinguished by the balsam scent of their buds, the whitish undersides of their leaves, and the leaf petiole being round in cross-section...
).
They are sympatric with Mandarin Duck
Mandarin Duck
The Mandarin Duck , or just Mandarin, is a medium-sized perching duck, closely related to the North American Wood Duck. It is 41–49 cm long with a 65–75 cm wingspan.-Description:...
s (Aix galericulata); though both relish the same insect larvae, they do not seem to compete for food, but perhaps for nesting holes (which neither can excavate themselves). In its winter quarters, the Scaly-sided Merganser might compete with other Merginae
Merginae
The seaducks, Merginae, form a subfamily of the duck, goose and swan family of birds, Anatidae.As the name implies, most but not all, are essentially marine outside the breeding season. Many species have developed specialized salt glands to allow them to tolerate salt water, but these have not yet...
with which it shares its habitat then, e.g. Common Merganser
Common Merganser
The Common Merganser or Goosander Mergus merganser is a large duck, of rivers and lakes of forested areas of Europe, northern and central Asia, and North America. It eats fish and nests in holes in trees...
s (M. merganser) and Common Goldeneye
Common Goldeneye
The Common Goldeneye is a medium-sized sea duck of the genus Bucephala, the goldeneyes. Their closest relative is the similar Barrow's Goldeneye....
s (Bucephala clangula).
Status
This speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
is considered endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
by the IUCN. Its numbers declined in the 1960s and 1970s due to loss of primary forests in its limited range, particularly along the major rivers. Current threats include illegal hunting, entanglement in fishing nets and river pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, as well as ongoing destruction of forest. According to its current IUCN classification EN C2a(ii), fewer than 2500 adult birds remain, and most of these are found in the region where the borders of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...
and Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
meet.
A confounding factor is that the Scaly-sided Merganser is rather solitary and extremely shy and alert. Thus, even though its range is still quite extensive, an accurate estimate of its population is difficult. A somewhat crude but nonetheless important indication of the Scaly-sided Merganser's population status may be gleaned by annual censuses on the lower Yangtze River
Yangtze River
The Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...
, which constitutes the single most important wintering area known to date. The mid-2000s assumption of a 20% or more decline in numbers til 2010 is discarded at present, because though the decline is certainly ongoing there is still too little data to quantify it that accurately.
External links
- ARKive - images and movies of the scaly-sided merganser (Mergus squamatus)
- BIrdLife species factsheet. Retrieved 2007-JUN-12.