EN
Hawaiian Duck Anas wyvilliana



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
- B1ab(ii,iii,iv,v) B1ab(ii,iii,iv,v)

Red List history
Year Category Criteria
2016 Endangered B1ab(ii,iii,iv,v)
2013 Endangered B1ab(ii,iii,iv,v)
2012 Endangered B1ab(ii,iii,iv,v)
2011 Endangered B1a+b(ii,iii,iv,v)
2008 Endangered B1a+b(ii,iii,iv,v)
2004 Endangered
2000 Endangered
1996 Vulnerable
1994 Vulnerable
1988 Threatened
Species attributes

Migratory status not a migrant Forest dependency Does not normally occur in forest
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 45,900 medium
Number of locations 11-100 -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 1500 medium estimated 2002
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) - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations 5 - - -
Largest subpopulations - - -
Generation length (yrs) 6.9 - - -

Population justification: The species's population is estimated to number c.2,200 individuals (K. Uyehara, A. Marshall and A. Engilis Jr. in litt. 2007), roughly equivalent to 1,500 mature individuals.

Trend justification: The species is suspected to be in decline owing to hybridisation, wetland loss and introduced predators, although the likely rate of decline has not been estimated.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
USA N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
USA Hanalei National Wildlife Refuge
USA Kealia Pond National Wildlife Refuge
USA Pearl Harbor National Wildlife Refuge

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Aquatic & Marine Artificial/Aquatic - Ponds (below 8ha) suitable resident
Forest Subtropical/Tropical Swamp marginal resident
Grassland Subtropical/Tropical Seasonally Wet/Flooded suitable resident
Marine Coastal/Supratidal Coastal Brackish/Saline Lagoons/Marine Lakes suitable resident
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) suitable resident
Wetlands (inland) Permanent Freshwater Marshes/Pools (under 8ha) suitable resident
Wetlands (inland) Permanent Rivers/Streams/Creeks (includes waterfalls) major resident
Altitude 0 - 3300 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Agro-industry farming Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Slow, Significant Declines Past Impact
Stresses
Species mortality
Climate change & severe weather Timing Scope Severity Impact
Past, Likely to Return Whole (>90%) Rapid Declines Past Impact
Stresses
Ecosystem degradation
Human intrusions & disturbance Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Species disturbance
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Named 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 Invasive non-native/alien species/diseases - Named species - Anas platyrhynchos Timing Scope Severity Impact
Ongoing Whole (>90%) Rapid Declines High Impact: 8
Stresses
Hybridisation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Named species - Canis familiaris Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Named species - Capra hircus Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Named species - Felis catus Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Named species - Herpestes javanicus_old 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 Invasive non-native/alien species/diseases - Named species - Sus domesticus Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Ongoing Whole (>90%) Rapid Declines High Impact: 8
Stresses
Hybridisation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation
Natural system modifications Timing Scope Severity Impact
Past, Unlikely to Return Minority (<50%) Unknown Past Impact
Stresses
Ecosystem conversion
Residential & commercial development Timing Scope Severity Impact
Past, Unlikely to Return Minority (<50%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion

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

Recommended citation
BirdLife International (2019) Species factsheet: Anas wyvilliana. Downloaded from http://www.birdlife.org on 20/05/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/05/2019.