EN
Scaly-sided Merganser Mergus squamatus



Taxonomy

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.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- C2a(ii) A2cd+3cd+4cd; C2a(ii)

Red List history
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
Species attributes

Migratory status full migrant Forest dependency High
Land mass type Land-mass type - continent
Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 733,000 medium
Extent of Occurrence non-breeding (km2) 7,710,000 medium
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 2400-4500 medium estimated 2012
Population trend Decreasing poor suspected -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 30-49 - - -
Decline (10 years/3 generation past and future) 30-49 - - -
Number of subpopulations 1 - - -
Largest subpopulations 100 - - -
Generation length (yrs) 7.3 - - -

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 distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
China (mainland) N Extant Yes
Japan N Extant Yes
Myanmar N Extant Yes
North Korea N Extant Yes
Russia N Extant Yes
Russia (Asian) N Extant Yes
South Korea N Extant Yes
Taiwan (China) N Extant Yes
Thailand N Extant Yes
Vietnam N Possibly Extinct

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
China (mainland) Baihe-Wanbao
China (mainland) Cang Shan Er Hai Nature Reserve
China (mainland) Changbai Shan Nature Reserve
China (mainland) Dashanzuizi
China (mainland) Dongting Hu wetlands
China (mainland) Fenglin Nature Reserve
China (mainland) Fujian Wuyi Shan Nature Reserve
China (mainland) Gaoyou Hu
China (mainland) Hanma Nature Reserve
China (mainland) Heiyupao Nature Reserve
China (mainland) Hukou Wetland Nature Reserve
China (mainland) Huma He Nature Reserve
China (mainland) Huzhong Nature Reserve
China (mainland) Jingpo Hu Nature Reserve
China (mainland) Keluo He Nature Reserve
China (mainland) Laodengshan Nature Reserve
China (mainland) Lashi Hai
China (mainland) Liangshui Nature Reserve
China (mainland) Mangui
China (mainland) Maoshan Nature Reserve
China (mainland) Mountains streams in Pingtang and Guiding
China (mainland) Mudanfeng Nature Reserve
China (mainland) Nansihu Nature Reserve
China (mainland) Nanweng He Nature Reserve
China (mainland) Naoli He Nature Reserve
China (mainland) Nuomin-Bila He-Dayangshu
China (mainland) Poyang Hu wetlands
China (mainland) Qindeli Sturgeon Reserve
China (mainland) Qingtongxia reservoir and Yellow River wetlands in Zhongning and Zhongwei
China (mainland) Qixing He Wetland Nature Reserve
China (mainland) Qixing Lazi Siberian Tiger Nature Reserve
China (mainland) Rongcheng Swan Nature Reserve
China (mainland) Sanjiang Nature Reserve
China (mainland) Shaobo Hu Lake Area
China (mainland) Shuifeng Reservoir and middle reaches of Yalu Jiang
China (mainland) Songhua Hu, Baishan Hu and Hongshi Hu
China (mainland) Tailai Dongfanghong
China (mainland) Wuyuan Forest
China (mainland) Xinjiang Yiyang Qinghu Section
China (mainland) Xunbiela He Nature Reserve
China (mainland) Yancheng Nature Reserve
China (mainland) Yangdali Nature Reserve
China (mainland) Yellow River Delta Nature Reserve
China (mainland) Yinchuan plain
China (mainland) Yueya Hu Nature Reserve
China (mainland) Yunfeng Reservoir
China (mainland) Zhejiang Qingliangfeng Nature Reserve
North Korea Mayang reservoir (Mayang Chosuji)
North Korea Mount Paekdu
North Korea Orangchon River estuary
Russia (Asian) Khanka plain
Russia (Asian) Kievka and Chernaya river basins
Russia (Asian) Lower Tumen river
Russia (Asian) Middle reaches of the Bikin river
Russia (Asian) Middle reaches of the Iman river
Russia (Asian) Sikhote-Alin' Nature Reserve
Russia (Asian) Udyl' lake

Habitats & altitude
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  

Threats & impact
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
Stresses
Species mortality
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
Stresses
Species mortality
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
Stresses
Ecosystem degradation, Ecosystem conversion
Human intrusions & disturbance Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Species disturbance
Natural system modifications Dams & water management/use - Dams (size unknown) Timing Scope Severity Impact
Future Minority (<50%) Slow, Significant Declines Low Impact: 3
Stresses
Ecosystem degradation, Ecosystem conversion
Pollution Agricultural & forestry effluents - Soil erosion, sedimentation Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Pollution Industrial & military effluents - Type Unknown/Unrecorded Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Residential & commercial development Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Rapid Declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Transportation & service corridors Timing Scope Severity Impact
Ongoing Minority (<50%) Rapid Declines Medium Impact: 6
Stresses
Indirect ecosystem effects, Species disturbance, Ecosystem degradation, Ecosystem conversion

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Food - human - - Non-trivial Recent
Sport hunting/specimen collecting - - Non-trivial Recent

Recommended citation
BirdLife International (2017) Species factsheet: Mergus squamatus. Downloaded from http://www.birdlife.org on 25/11/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/11/2017.