• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic note

Hemignathus wilsoni (del Hoyo and Collar 2016) was previously listed as H. munroi following AOU (1998 & supplements); Sibley & Monroe (1990, 1993).

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	B1ab(i,ii,iii,iv,v)	B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v); D2

Red List history

Year	Category	Criteria
2023	Endangered	B1ab(i,ii,iii,iv,v)
2016	Endangered	B1ab(i,ii,iii,iv,v); C2a(ii)
2013	Endangered	B1ab(i,ii,iii,iv,v)
2012	Endangered	B1ab(i,ii,iii,iv,v)
2008	Endangered	B1a+b(i,ii,iii,iv,v)
2004	Endangered
2000	Endangered
1996	Endangered
1994	Endangered
1988	Threatened

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	1,300 km2	medium
Area of Occupancy (breeding/resident)	832 km2
Number of locations	1	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	1300 mature individuals	good	estimated	2009
Population trend	decreasing	good	inferred	-
Generation length	3.34 years	-	-	-
Number of subpopulations	2	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

Population justification: In 1976-1979 and 1983, surveys estimated c.1,500 birds, with 900 in Hamakua, 500 in Ka`u, 50 on Mauna Kea, and 20 in central Kona (Scott et al. 1986). In 1990-1995, surveys estimated 1,163, with 1,105 in Hamakua, c.44 in Ka`u, fewer than 10 on Mauna Kea (and only a few males by 1999 [T. Pratt in litt. 1999]), and perhaps fewer than 10 in Kona (Fancy et al. 1996). The population on western Mauna Kea has since been extirpated (VanderWerf 2012). The species' population in Ka`u was estimated at 1,073 individuals (95% CI: 616-1,869) in 2005 (Gorresen et al. 2007). It should be noted that this higher population estimate in Ka`u does not represent a genuine population increase, but an improvement in survey methodology. Surveys conducted during 2003-2004 in the Kapapala Forest Reserve reported 35 individuals (including 14 families) in c. 650 ha of the reserve (Pratt et al. 2009). The population at the Kona Forest National Wildlife Refuge may also now be extirpated (Fancy et al. 1996, Camp et al. 2009). The global population was estimated at 1,900 birds in 2009 (Gorreson et al. 2009), roughly equivalent to 1,300 mature individuals overall, with 1,163 birds (95% CI: 507-2,401) occurring in Hakalau Forest National Wildlife Refuge (Kendall et al. 2022).

Trend justification: Surveys in 1990-1995 suggested a decline of c.22.5% over the previous 13 years (Fancy et al. 1996). The species is extirpated from subalpine Mauna Kea and likely Kona districts (Gorresen et al. 2009). Surveys from 1977 to 2003 indicate that the species may have declined in the Keauhou-Kulani area (Gorresen et al. 2005). In the Ka`u District of Hawai`i, surveys from 1976 to 2005 indicate that the species has been extirpated from habitat below 1,500 m, with no change in the density of populations at high elevations (Gorresen et al. 2007). Trends at Hakalau Forest National Wildlife Refuge and in the upper portions of the Ka‘? Forest Reserve were previously thought to be increasing and stable, respectively (Camp et al. 2009, 2010). In a recent analysis of annual population density estimates in Hakalau Forest National Wildlife Refuge, which supports c.61% of the population, trends were negative in the closed-forest stratum in the period 1987-2019. In the most recent decade 2010-2019, density declined by more than 10% in the closed-forest stratum, although the trend was inconclusive for open-forest and increasing in restored pasture (Kendall et al. 2022). Trends are unknown in central windward Hawai‘i and Ka‘? regions (USFWS 2020). The population is inferred to be declining overall given ongoing range contraction, and this is predicted to continue given that the threats are ongoing. Given that the species is highly susceptible to avian malaria, climate change is likely to reduce the area of suitable remaining habitat and drive further declines through causing an increase in the elevation below which regular transmission occurs (USWFS 2020).

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
USA	extant	native	yes

Country/Territory	IBA Name
USA	Hamakua Forests
USA	Kau Forest
USA	Mauna Loa-Kilauea Forests

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Dry	major	resident
Forest	Subtropical/Tropical Moist Montane	major	resident
Altitude	1300 - 2100 m	Occasional altitudinal limits	(max) 2900 m

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Livestock farming & ranching - Agro-industry grazing, ranching or 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	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Majority (50-90%)		Slow, Significant Declines		Past Impact
		Stresses Ecosystem degradation, Ecosystem conversion
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Ongoing		Whole (>90%)		Slow, Significant Declines		Medium Impact: 7
		Stresses Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - 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 - Plasmodium relictum	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus rattus	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 - Sus domesticus	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation
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 Ecosystem degradation
Invasive and other problematic species, genes & diseases	Problematic native species/diseases - Unspecified species	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Problematic species/disease of unknown origin - Named species	Timing		Scope		Severity		Impact
		Ongoing		Unknown		Unknown		Unknown
		Stresses Reduced reproductive success
Invasive and other problematic species, genes & diseases	Viral/prion-induced diseases - Avipoxvirus	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Species mortality

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Recommended citation
BirdLife International (2024) Species factsheet: Akiapolaau Hemignathus wilsoni. Downloaded from https://datazone.birdlife.org/species/factsheet/akiapolaau-hemignathus-wilsoni on 23/11/2024.
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 23/11/2024.