VU
Japanese Night-heron Gorsachius goisagi



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)

Red List history
Year Category Criteria
2020 Vulnerable C2a(ii)
2016 Endangered C2a(i)
2012 Endangered C2a(i)
2008 Endangered C2a(i)
2004 Endangered
2000 Endangered
1996 Vulnerable
1994 Vulnerable
1988 Threatened
Species attributes

Migratory status full migrant Forest dependency High
Land mass type Land-mass type - continent
Average mass -
Distribution

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 1,010,000 medium
Extent of Occurrence non-breeding (km2) 1,440,000 medium
Number of locations 11-100 -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals 5000-9999 poor suspected 2014
Population trend Decreasing poor inferred -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 1-9 - - -
Decline (10 years/3 generation past and future) 1-9 - - -
Number of subpopulations 1 - - -
Percentage in largest subpopulation 100 - - -
Generation length (yrs) 5.5 - - -

Population justification: Previous work in Japan suggests the assertion that the global population comprises fewer than 1,000 individuals may have been overly pessimistic. These estimations are however not considered accurate by some researchers (K. Kawakami in litt. 2016). Recent mating call detections however recorded 23 individuals per 100 km2 in rural secondary forests across the Aichi Prefecture in central Japan (Hamaguchi et al. 2014). The total area of rural secondary forests in Honshu, Kyushu and Shikoku islands estimates to 72,000 km2 (Watanabe et al. 2012). Thus, the number of mature individuals is thought to be approximately 8,280. However, mating call detection studies have been considered as an unreliable method of monitoring breeding numbers in this instance due to the species's inconspicuous habits and the potential of receiving duplicated records (K. Ohata in litt. 2020). Similar calling surveys have for example not recorded any nests, and as such breeding birds, despite observing other calling individuals. It is also likely that surveys specific to limited sites (the Aichi area in this instance), may not yield results that are compatible with other suitable habitats across the species's range (K. Ohata in litt. 2020). Habitat models have additionally been considered impractical methods of estimating population numbers or trends (J. Kushlan in litt. 2020). Hence, to account for any uncertainty, the true figure is placed here in the band of 5,000-9,999 mature individuals, roughly equating to 7,500-15,000 individuals. As per the Waterbird Population Estimates, the species is also thought to occur in only one flyaway population across Eastern and South-eastern Asia (Wetlands International 2020). This is assumed to represent one subpopulation holding all mature individuals.

Trend justification: The species had previously considered to have undergone rapid declines due to deforestation and habitat conversion (Martinez-Vilalta et al. 2020). However, recent forest loss estimates show a negligible decline (Tracewski et al. 2016, Global Forest Watch 2020), equating to 3% over three generations (16.5 years; Bird et al. 2020). Forest destruction is also considered to no longer be a threat across breeding sites in Japan (S. Chan in litt. 2020). However, the population is thought to be rapidly declining at migratory and wintering grounds (S. Chan in litt. 2020), primarily owed to hunting pressure. Breeding areas may also suffer from problematic native and non-native species, as well as some level of continued habitat degradation. Thus, the population is inferred to be undergoing a continued decline of 1-9% over three generations.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Brunei V Extant Yes
China (mainland) N Extant Yes Yes
Hong Kong (China) N Extant Yes
Indonesia V Extant Yes
Japan N Extant Yes
Palau V Extant Yes
Philippines N Extant Yes
Russia V Extant Yes
Russia (Asian) V Extant Yes
South Korea N Extant Yes Yes
Taiwan, China N Extant Yes
Vietnam V Extant

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Indonesia Tangkoko Dua Sudara
Indonesia Mahawu - Masarang
Philippines University of the Philippines Land Grants (Pakil and Real)
Philippines Quezon National Park
Philippines Victoria and Anepahan Ranges
Philippines Central Panay mountains
Philippines Cuernos de Negros
Philippines Mount Bandila-an
Philippines Mount Hilong-hilong
Philippines Mount Kampalili-Puting Bato
Philippines Mount Hamiguitan (Tumadgo peak)
Philippines Liguasan marsh
Philippines Mount Busa-Kiamba
Philippines Mount Latian complex
Philippines Pasonanca watershed
Russia (Asian) Lower Tumen river
Philippines Mount Malindang
Japan Hachirogata
Japan Mount Hyonosen
Indonesia Morowali

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Arable Land suitable non-breeding
Forest Subtropical/Tropical Dry suitable non-breeding
Forest Subtropical/Tropical Dry suitable breeding
Forest Subtropical/Tropical Moist Lowland major non-breeding
Forest Subtropical/Tropical Moist Lowland major breeding
Forest Subtropical/Tropical Moist Montane major non-breeding
Forest Subtropical/Tropical Moist Montane major breeding
Forest Temperate major breeding
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable non-breeding
Altitude 0 - 2400 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Shifting agriculture Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Species mortality
Biological resource use Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Ecosystem degradation
Energy production & mining Renewable energy Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Geological events Volcanoes Timing Scope Severity Impact
Past, Likely to Return Minority (<50%) Rapid Declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Mustela sibirica Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Problematic native species/diseases - Cervus nippon Timing Scope Severity Impact
Ongoing Minority (<50%) Causing/Could cause fluctuations Low Impact: 5
Stresses
Species disturbance, Ecosystem conversion, Reduced reproductive success
Residential & commercial development Commercial & industrial areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Residential & commercial development Tourism & recreation areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Food - human - - Non-trivial Recent
Handicrafts, jewellery, etc. - - Non-trivial Recent
Pets/display animals, horticulture - - International Non-trivial Recent

Recommended citation
BirdLife International (2021) Species factsheet: Gorsachius goisagi. Downloaded from http://www.birdlife.org on 04/12/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/12/2021.