Data Zone
Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
| Critically Endangered | Endangered | Vulnerable |
|---|---|---|
| - | C2a(ii) | A2cd+3cd+4cd; C2a(ii) |
| Year | Category | Criteria |
|---|---|---|
| 2016 | Endangered | C2a(ii) |
| 2012 | Endangered | C2a(ii) |
| 2009 | Endangered | C2a(ii) |
| 2008 | Endangered | |
| 2007 | Endangered | |
| 2006 | Endangered | |
| 2004 | Endangered | |
| 2002 | Endangered | |
| 2000 | Vulnerable | |
| 1996 | Vulnerable | |
| 1994 | Vulnerable | |
| 1988 | Threatened |
| Migratory status | full migrant | Forest dependency | high |
| Land-mass type |
continent |
Average mass | - |
| Estimate | Data quality | |
|---|---|---|
| Extent of Occurrence (breeding/resident) | 731,000 km2 | medium |
| Extent of Occurrence (non-breeding) | 7,720,000 km2 | medium |
| Severely fragmented? | no | - |
| Estimate | Data quality | Derivation | Year of estimate | |
|---|---|---|---|---|
| Population size | 2400-4500 mature individuals | medium | estimated | 2012 |
| Population trend | decreasing | poor | suspected | 2005-2027 |
| Rate of change over the past 10 years/3 generations (longer of the two periods) | 30-49% | - | - | - |
| Rate of change over the future 10 years/3 generations (longer of the two periods) | 30-49% | - | - | - |
| Rate of change over the past & future 10 years/3 generations (longer of the two periods) | 30-49% | - | - | - |
| Generation length | 7.3 years | - | - | - |
| Number of subpopulations | 1 | - | - | - |
| Percentage of mature individuals in largest subpopulation | 100% | - | - | - |
Population justification: In Russia, c.1,643 pairs nest in Sikhote-Alin (Solovyeva et al. 2014), with just 11 pairs estimated to nest north of the Amur river. In China, 155 pairs breed in the Changbai Mountains and 11 pairs in Lesser Xingan (Solovyeva et al. 2014). In North Korea, breeding occurs at Mayang Chosuji reservoir and 116 pairs are estimated to breed in the Changbai Mountains (Chong and Morishita 1996, Solovyeva et al. 2014). Pair densities were found to be highest on the Fuerhe River in the Chinese Changbai Mountains (0.918 pairs/km) and on the Pavlovka River in Sikhote-Alin (0.63 pairs/km) (Solovyeva et al. 2014). The total world population is therefore estimated at 1,936 pairs (Solovyeva et al. 2014). There are, however, other estimates of perhaps several thousand pairs (B. Hughes in litt. 2010). In recognition of these uncertainties, the number of mature individuals is estimated at 2,400-4,500, following Peiqi Liu et al. (2010). This is roughly equivalent to 3,600-6,800 individuals in total. Further research is required in order to verify this.
Trend justification: A rapid and on-going population decline is suspected (see BirdLife International 2001). The density of breeding pairs more than doubled since the 1960s/1970s in the species's stronghold in Russia, but has since stabilised (Solovieva et al. 2006). The Changbai (China) breeding population may be increasing, but the western population (found in Xingan, China and Zeya-Bureya, Russia) has declined rapidly.
| Country/Territory | Presence | Origin | Resident | Breeding visitor | Non-breeding visitor | Passage migrant |
|---|---|---|---|---|---|---|
| China (mainland) | extant | native | yes | |||
| Japan | extant | native | yes | |||
| Myanmar | extant | native | yes | |||
| North Korea | extant | native | yes | |||
| Russia | extant | native | yes | |||
| Russia (Asian) | extant | native | yes | |||
| South Korea | extant | native | yes | |||
| Taiwan, China | extant | native | yes | |||
| Thailand | extant | native | yes | |||
| Vietnam | possibly extinct | native |
| Habitat (level 1) | Habitat (level 2) | Importance | Occurrence |
|---|---|---|---|
| Forest | Temperate | major | breeding |
| Marine Neritic | Estuaries | suitable | non-breeding |
| Marine Neritic | Subtidal Sandy | suitable | non-breeding |
| Wetlands (inland) | Permanent Freshwater Lakes (over 8ha) | suitable | non-breeding |
| Wetlands (inland) | Permanent Rivers/Streams/Creeks (includes waterfalls) | major | breeding |
| Wetlands (inland) | Permanent Rivers/Streams/Creeks (includes waterfalls) | major | non-breeding |
| Altitude | 0 - 900 m | Occasional altitudinal limits |
| Threat (level 1) | Threat (level 2) | Impact and Stresses | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Biological resource use | Fishing & harvesting aquatic resources - Unintentional effects: (subsistence/small scale) [harvest] | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Slow, Significant Declines | Low Impact: 5 | ||||||
|
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| Biological resource use | Hunting & trapping terrestrial animals - Intentional use (species is the target) | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Rapid Declines | Medium Impact: 6 | ||||||
|
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| Biological resource use | Logging & wood harvesting - Unintentional effects: (large scale) [harvest] | Timing | Scope | Severity | Impact | ||||
| Ongoing | Majority (50-90%) | Slow, Significant Declines | Medium Impact: 6 | ||||||
|
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| Human intrusions & disturbance | Work & other activities | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Slow, Significant Declines | Low Impact: 5 | ||||||
|
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| Natural system modifications | Dams & water management/use - Dams (size unknown) | Timing | Scope | Severity | Impact | ||||
| Future | Minority (<50%) | Slow, Significant Declines | Low Impact: 3 | ||||||
|
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| Pollution | Agricultural & forestry effluents - Soil erosion, sedimentation | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Slow, Significant Declines | Low Impact: 5 | ||||||
|
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| Pollution | Industrial & military effluents - Type Unknown/Unrecorded | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Slow, Significant Declines | Low Impact: 5 | ||||||
|
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| Residential & commercial development | Commercial & industrial areas | Timing | Scope | Severity | Impact | ||||
| Past, Unlikely to Return | Majority (50-90%) | Rapid Declines | Past Impact | ||||||
|
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| Transportation & service corridors | Shipping lanes | Timing | Scope | Severity | Impact | ||||
| Ongoing | Minority (<50%) | Rapid Declines | Medium Impact: 6 | ||||||
|
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| Purpose | Scale |
|---|---|
| Food - human | subsistence, national |
| Sport hunting/specimen collecting | subsistence, national |
Recommended citation
BirdLife International (2024) Species factsheet: Scaly-sided Merganser Mergus squamatus. Downloaded from
https://datazone.birdlife.org/species/factsheet/scaly-sided-merganser-mergus-squamatus on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.