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Corvus hawaiiensis 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Corvidae

Scientific Name: Corvus hawaiiensis
Species Authority: Peale, 1848
Common Name(s):
English Hawaiian Crow
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.
Identification information: 48 cm. Large crow or small raven. All dark sooty-brown with paler primaries. Heavy, black bill. Brown eyes. Juvenile has blue eyes and pink mouth lining. Voice Huge variety of squawks, screams, growls, and dissonant croaks. Hints Flies high over montane forest and ridges.

Assessment Information [top]

Red List Category & Criteria: Extinct in the Wild ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Baker, P.E., Banko, P., Burgett, J., Camp, R., Fretz, S., Gorresen, M., Lieberman, A., Pimm, S., VanderWerf, E., Woodworth, B. & Nelson, J.
Facilitator/Compiler(s): Benstead, P., Capper, D., Derhé, M., Isherwood, I., Stattersfield, A., Stuart, T., Symes, A., Taylor, J., Martin, R
Justification:
The last two known wild individuals of this species disappeared in 2002, so the species is now classified as Extinct in the Wild. Some individuals remain in captive breeding facilities and a reintroduction plan is being developed.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Corvus hawaiiensis was distributed historically on Hawai`i in the Hawaiian Islands (USA), where the last individuals were found in and around the Kona Forest Unit of Hakalau Forest National Wildlife Refuge. Bones of this or a closely related species have been found on Maui, indicating a wider distribution before Western contact (Banko et al. 2002, Banko 2009). Nesting by the last known wild birds was probably confined to higher elevations on Mauna Loa in South Kona (Faike 2006, Banko 2009).

Countries occurrence:
Regionally extinct:
United States (Hawaiian Is.)
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):300
Upper elevation limit (metres):2000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In 1992, there were only 11 or 12 birds in the wild (Maxfield 1998, Banko et al. 2002, Banko 2009), and the last two individuals were last seen in June 2002. The last known wild chick fledged in 1992, and the last viable wild egg was laid in 1996 (Faike 2006). The species persists in captive breeding facilities, with development of a reintroduction programme in progress (Lieberman and Kuehler 2009, U.S. Fish and Wildlife Service 2009). Captive breeding started in the 1970s, but few fledglings were produced until eggs from wild nests were harvested and hatched in captivity during 1993-1996 (Lieberman and Kuehler 2009, Banko 2009). A total of 27 captive-reared juveniles, originating from eggs laid either in the wild or in captivity, were released during 1993-1999 (Banko 2009, U.S. Fish and Wildlife Service 2009). By 1999, 21 released birds had died and the remaining six were captured to protect them and preserve genetic diversity (Maxfield 1998, Conrow 1999, Banko 2009, U.S. Fish and Wildlife Service 2009). In 2011, the captive population stood at 94 individuals (49 at the Keauhou Bird Conservation Center, 44 at the Maui Bird Conservation Center, and 1 at the San Diego Zoo), including 39 birds used as breeders (Switzer 2011).
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:It once inhabited dry to moist `ohi`a-koa forest and woodlands, but it later became confined to high mountain forest. It is omnivorous, but primarily feeds on the fruit of native understory plants (Maxfield 1998, USFWS and Hawai'i DLNR 1999). As well as fruits and berries, the species feeds on eggs, young birds, insects and carrion (Faike 2006). Captive-reared birds have been observed using twigs as tools to access food (Faike 2006). Nest construction usually begins in March and the first clutches are laid in April (Banko et al. 2003).

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):7.3
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): It has suffered from extensive habitat alteration, particularly reduction of understory food-plants as a result of the activities of feral ungulates, logging, agriculture and the loss of pollinators and dispersers (U.S. Fish and Wildlife Service 2009). Problematic ungulates include feral cattle, mouflon sheep, feral sheep and goats (J. Burgett in litt. 2007). The impact of shooting has probably been substantial, even in recent decades. In the late 19th Century, the species was persecuted as a pest, and it became unpopular with pig hunters for alerting animals to their presence (Faike 2006). The species was confiding and easily attracted by imitated calls, making it an easy target (Faike 2006). During breeding the species is sensitive to human disturbance (Faike 2006), including nest-monitoring operations (Banko et al. 2002, Walters 2006). Other documented threats include predation by introduced rats, the small Asian mongoose Herpestes javanicus and the native Hawaiian Hawk Buteo solitarius (classified as Near Threatened), as well as avian malaria and pox carried by introduced mosquitoes (Maxfield 1998) and Toxoplasma gondii carried by feral cats (Banko et al. 2002, J. Burgett in litt. 2007, Banko 2009, U.S. Fish and Wildlife Service 2009). Feral cats are ubiquitous in the species's habitat and are also potential predators (J. Burgett in litt. 2007). Fledged chicks remain near the ground for several days before they can fly properly and are at particular risk from predation (Faike 2006, Banko et al. 2002). Captive-reared birds have suffered from disease, with at least one dying from a bacterial infection, and diseases may have made others more vulnerable to predation (Maxfield 1998, Banko et al. 2002, Banko 2009, U.S. Fish and Wildlife Service 2009). The captive population is inbred (Faike 2006, U.S. Fish and Wildlife Service 2009), and this may be reducing reproductive success. West Nile Virus, which could potentially be introduced by migrating shorebirds and waterfowl or commercial transport, and is spread by mosquitoes (Faike 2006), could threaten reintroduction efforts in the future. West Nile Virus is presumed to be highly lethal in C. hawaiiensis, owing to a reduction in the population of the American Crow C. brachyrhynchos in mainland North America by 45% over eight years due to the virus (J. Burgett in litt. 2007).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Between 1993 and 2007, over 90 birds were hatched in the captive breeding programme (Lieberman and Kuehler 2009). Captive-raised individuals were released into lightly-managed habitat and monitored (Kuehler et al. 1994, Lieberman 1997, Banko 2009), but releases were stopped after January 1999 due to increasing mortality (U.S. Fish and Wildlife Service 2009). About 75 birds need to be maintained in the captive flock for future reintroduction attempts to take place (U.S. Fish and Wildlife Service 2009). In 2011, the captive population stood at 94 individuals, including 39 birds used as breeders (Switzer 2011). Introduced mammalian predators were trapped in the Kona Forest Unit and, although this no longer takes place, predators will be managed at any future reintroduction sites (J. Burgett in litt. 2007). Some areas of its former range are now fenced and free of feral ungulates, and the exclusion of ungulates will be extended into other areas (J. Burgett in litt. 2007). Relocation of problematic B. solitarius failed because the birds homed back from over 32 km (U.S. Fish and Wildlife Service 2009). Two reintroduction sites have now been identified (Nelson in litt. 2012). Following ungulate removal, fencing and habitat restoration, reintroduction at Puʻu Makaʻala Natural Area Reserve is due to begin with the release of 6 birds hatched in 2016. Ongoing restoration effort continues at the second site. A recovery plan was prepared in 1982 and revised in 2009, outlining recovery actions including expanding the captive propagation to minimize loss of genetic diversity, protecting suitable habitat and managing threats to the species, establishing new populations in managed habitat, establishing a program to increase public support, and continuing research and adaptive management practices for species recovery (USFWS 2009). Each year, around 2,000 school children and students attend the environmental education programme and see C. hawaiiensis in captivity at the Keauhou Bird Conservation Centre (Faike 2006).

Conservation Actions Proposed
Restore and manage a significant proportion of remaining habitat within the species's historical range. Deal creatively with the problem posed by B. solitarius (Maxfield 1998, P. Baker in litt. 1999, U.S. Fish and Wildlife Service 2009). Develop captive breeding programmes and reintroduce birds to habitat managed to reduce major threats. Exclude ungulates from more areas of habitat. Control potential predators and vectors of disease in the species's former range.

Classifications [top]

1. Forest -> 1.5. Forest - Subtropical/Tropical Dry
suitability:Suitable season:resident major importance:No
1. Forest -> 1.6. Forest - Subtropical/Tropical Moist Lowland
suitability:Suitable season:resident major importance:Yes
1. Forest -> 1.9. Forest - Subtropical/Tropical Moist Montane
suitability:Suitable season:resident major importance:Yes
3. Shrubland -> 3.5. Shrubland - Subtropical/Tropical Dry
suitability:Suitable season:resident major importance:No
3. Shrubland -> 3.6. Shrubland - Subtropical/Tropical Moist
suitability:Suitable season:resident major importance:Yes
14. Artificial/Terrestrial -> 14.2. Artificial/Terrestrial - Pastureland
suitability:Suitable season:resident major importance:No
2. Land/water management -> 2.2. Invasive/problematic species control
2. Land/water management -> 2.3. Habitat & natural process restoration
3. Species management -> 3.3. Species re-introduction -> 3.3.1. Reintroduction
3. Species management -> 3.4. Ex-situ conservation -> 3.4.1. Captive breeding/artificial propagation

In-Place Research, Monitoring and Planning
  Action Recovery plan:Yes
  Systematic monitoring scheme:No
In-Place Land/Water Protection and Management
  Conservation sites identified:Yes, over part of range
  Occur in at least one PA:No
  Invasive species control or prevention:Yes
In-Place Species Management
  Successfully reintroduced or introduced beningly:No
  Subject to ex-situ conservation:Yes
In-Place Education
  Subject to recent education and awareness programmes:Yes
  Included in international legislation:No
  Subject to any international management/trade controls:No
2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.3. Agro-industry farming
♦ timing:Past, Unlikely to Return ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Past Impact 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

5. Biological resource use -> 5.1. Hunting & trapping terrestrial animals -> 5.1.3. Persecution/control (Bos taurus (
♦ timing:Past, Unlikely to Return ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Past Impact 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

5. Biological resource use -> 5.3. Logging & wood harvesting -> 5.3.4. Unintentional effects: (large scale) [harvest]
♦ timing:Past, Unlikely to Return ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Past Impact 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

6. Human intrusions & disturbance -> 6.3. Work & other activities
♦ timing:Past, Likely to Return ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Past Impact 
→ Stresses
  • 2. Species Stresses -> 2.2. Species disturbance
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Rattus exulans ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Capra hircus ]
♦ timing:Ongoing ♦ scope:Minority (<50%) ♦ severity:Negligible declines ⇒ Impact score:Low Impact: 4 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Felis catus ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Bos taurus ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Ovis aries ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Herpestes javanicus_old ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Rattus rattus ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Toxoplasma gondii ]
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Plasmodium relictum ]
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive and other problematic species, genes & diseases -> 8.2. Problematic native species/diseases -> 8.2.2. Named species [ Buteo solitarius ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive and other problematic species, genes & diseases -> 8.5. Viral/prion-induced diseases -> 8.5.2. Named species (Toxoplasma gondii (
♦ timing:Future ♦ scope:Whole (>90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Low Impact: 5 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive and other problematic species, genes & diseases -> 8.5. Viral/prion-induced diseases -> 8.5.2. Named species
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

Bibliography [top]

Anon. 2009. Revised recovery plan for 'Alala released. 'Elepaio 69(5): 37.

Banko, P. C., Ball, D. L., Banko, W. E. 2002. Hawaiian crow (Corvus hawaiiensis). In: A. Poole and F. Gill (eds), The Birds of North America, No. 648, The Birds of North America, Inc, Philadelphia, PA.

Banko, P. C.; Burgett, J.; Conry, P. J.; David, R.; Derrickson, S.; Fitzpatrick, J.; Liebermann, A.; Nelson, J. T.; Simmons, P.; Unger, K.; Vitousek, P. M. 2003. Draft revised recovery plan for the Alala (Corvus Hawaiiensis. US Fish and Wildlife Service, Portland, OR, USA.

Collar, N. J.; Butchart, S. H. M. 2013. Conservation breeding and avian diversity: chances and challenges. International Zoo Yearbook 48(1): 7-28.

Conrow, J. 1999. Born to be wild. Audubon 101: 64-71.

Faike, E. 2006. Wild voices in captivity: the date of the 'Alala. Birding 38: 64-67.

IUCN. 2016. The IUCN Red List of Threatened Species. Version 2016-3. Available at: www.iucnredlist.org. (Accessed: 07 December 2016).

Kuehler, C.; Kuhn, M.; McIlraith, B.; Campbell, G. 1994. Artificial incubation and hand-rearing of Alala Corvus hawaiiensis eggs removed from the wild. Zoo Biology 13: 257-266.

Lieberman, A. 1997. Conservation of the Hawaiian Avifauna. AFA Watchbird 24: 28.

Lieberman, A. C., Kuehler, C. M. 2009. Captive propagation. In: Pratt, T. K.; Atkinson, C. T.; Banko, P. C.; Jacobi, J. D.; Woodworth, B. L. (ed.), Conservation Biology of Hawaiian Forest Birds: Implications for Island Avifauna, pp. 448-469. Yale University Press, New Haven.

Maxfield, B. 1998. Wild 'Alala population suffers major setback. 'Elepaio 58: 51.

Switzer, R. 2011. Hawaii Endangered Bird Conservaton Program Report. In: Lieberman, A. (ed.), Report to U.S. Fish and Wildlife Service and State of Hawaii. San Diego Zoo Global Institutue for Conservation Research, The Zoological Society of San Diego, Keauhou Bird Conservation Center and Maui Bird Conservation Center.

US Fish & Wildlife Service. 2009. Revised Recovery Plan for the 'Alala (Corvus hawaiiensis). Available at: #http://ecos.fws.gov/docs/recovery_plan/090417.pdf#.

USFWS and Hawaii DLNR. 1999. US Fish and Wildlife Service and Hawai'i DLNR, Honolulu, USA.

Walters, M. J. 2006. Do no harm [Hawaiian Crow]. Conservation in Practice 7(4): 28-32.


Citation: BirdLife International. 2016. Corvus hawaiiensis. The IUCN Red List of Threatened Species 2016: e.T22706052A94048187. . Downloaded on 10 December 2016.
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