Anas wyvilliana

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

View Printer Friendly

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	ANSERIFORMES	ANATIDAE

Scientific Name:

Anas wyvilliana

Species Authority:

Sclater, 1878

Common Name/s:

English

–

Hawaiian Duck, Koloa

Assessment Information [top]

Red List Category & Criteria:

Endangered B1ab(ii,iii,iv,v) ver 3.1

Year Assessed:

2011

Assessor/s:

BirdLife International

Reviewer/s:

Taylor, J., Butchart, S.

Contributor/s:

Marshall, A., Baker, P., Baker, H., Duvall, F., Woodworth, B., Donaldson, P., Pratt, H., Camp, R., Telfer, T., Engilis, Jr., A., Uyehara, K., Morin, M., Fretz, S., Gorresen, M., VanderWerf, E.

Justification:
This species qualifies as Endangered because it is inferred to have a very small and fragmented range on a few islands, where wetlands are being lost and degraded, and where hybridisation is slowly reducing the number of pure individuals.

History:

2008	–	Endangered
2004	–	Endangered
2000	–	Endangered
1996	–	Vulnerable
1994	–	Vulnerable

Geographic Range [top]

Range Description:	Anas wyvilliana was once an inhabitant of all the main Hawaiian Islands (USA) except Lâna`i and Kaho`olawe¹⁴, but is now restricted to Kaua`i and Ni`ihau, and is reintroduced on O`ahu, Hawai`i and Maui. Its population was estimated to number 2,525 individuals¹³, but this has been revised to 2,200¹⁶, with c.2,000 on Kaua`i and Ni`ihau and c.200 on Hawai`i^3,7,14,16. In 1997, 5-11 were seen on Maui⁶. In addition, some of the c.300 birds on O`ahu and c.50 birds on Maui that resemble A. wyvilliana are pure birds¹⁴. However, most of the birds on these two islands are A. platyrhynchos x A. wyvilliana hybrids. The distribution and abundance of the species is not clear in some areas due to difficulties in the identification and distinguishing of hybrids¹⁴.
Countries:	Native: United States
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	The species's population is estimated to number c.2,200 individuals (K. Uyehara, A. Marshall and A. Engilis Jr. in litt. 2007).
Population Trend:	Decreasing

Population:

The species's population is estimated to number c.2,200 individuals (K. Uyehara, A. Marshall and A. Engilis Jr. in litt. 2007).

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	It inhabits wetlands, including coastal ponds, lakes, swamps, flooded grasslands, mountain streams, anthropogenic water-bodies and occasionally boggy forests, as high as 3,300 m^11,12. Breeding occurs year-round, with the majority of breeding records from March to June¹⁶. It is an opportunistic feeder, taking invertebrates, seeds and plant matter¹⁴.
Systems:	Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s):	A significant population decline in the early 20th century was brought about by nest predation by rats, mongooses, domestic dogs and cats, introduced fish and birds, habitat loss for agriculture and urban development, and local hunting pressure¹⁴. The indiscriminate hunting of migratory waterbirds in the late 1800s and early 1900s took a heavy toll on the species's population¹⁴. Presently, hybridisation with feral A. platyrhynchos, and therefore the danger of genetic introgression, is the primary threat to the species's recovery¹⁴. A. platyrhynchos was first imported to Hawaii in the late 1800s for ornamental ponds and farming, and in the 1950s and 1960s, hundreds were imported to stock hunting areas¹⁵. On O`ahu, Maui and Hawai`i there are very few pure birds remaining^4,7,15,16 with the probable exception (on the latter) of birds at high elevations on Kohala and Mauna Kea, where there are few feral A. platyrhynchos^7,8,15,16. Hybridisation appears to be beginning on Kaua`i, the species's largest population and so far largely free of hybrids¹⁴. Wetland loss and habitat modification by alien aquatic plants are also threats⁹. Pigs, goats and other feral ungulates may degrade nesting habitat¹⁴. On O`ahu at least, artificial wetlands associated with sugarcane plantations and aquaculture have disappeared as these industries have declined on the island⁵. Introduced predators (such as the small Asian mongoose Herpestes javanicus, rats, cats and dogs) are an additional factor¹¹. The species is also threatened by drought and human disturbance from recreation and tourism¹⁶.

Major Threat(s):

A significant population decline in the early 20th century was brought about by nest predation by rats, mongooses, domestic dogs and cats, introduced fish and birds, habitat loss for agriculture and urban development, and local hunting pressure¹⁴. The indiscriminate hunting of migratory waterbirds in the late 1800s and early 1900s took a heavy toll on the species's population¹⁴. Presently, hybridisation with feral A. platyrhynchos, and therefore the danger of genetic introgression, is the primary threat to the species's recovery¹⁴. A. platyrhynchos was first imported to Hawaii in the late 1800s for ornamental ponds and farming, and in the 1950s and 1960s, hundreds were imported to stock hunting areas¹⁵. On O`ahu, Maui and Hawai`i there are very few pure birds remaining^4,7,15,16 with the probable exception (on the latter) of birds at high elevations on Kohala and Mauna Kea, where there are few feral A. platyrhynchos^7,8,15,16. Hybridisation appears to be beginning on Kaua`i, the species's largest population and so far largely free of hybrids¹⁴. Wetland loss and habitat modification by alien aquatic plants are also threats⁹. Pigs, goats and other feral ungulates may degrade nesting habitat¹⁴. On O`ahu at least, artificial wetlands associated with sugarcane plantations and aquaculture have disappeared as these industries have declined on the island⁵. Introduced predators (such as the small Asian mongoose Herpestes javanicus, rats, cats and dogs) are an additional factor¹¹. The species is also threatened by drought and human disturbance from recreation and tourism¹⁶.

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway On Kaua`i, the Hanalei National Wildlife Refuge is an important area for the species, especially in winter¹². The species was reintroduced to O`ahu through the release of 326 captive-bred birds between 1958 and 1982¹⁴; in 1989, fewer than 12 captive-bred birds were released on Maui; and between 1976 and 1982, the species was reestablished on Hawai`i also through the release of captive-bred birds¹⁴. In the late 1980s, the importation of A. platyrhynchos was restricted by the state, with exceptions only for research and exhibition¹⁵. In 2002, the department of agriculture placed an embargo on all birds shipped to the Hawaiian islands, to protect the public from West Nile Virus. Research is being carried out to develop techniques for the identification of hybrids¹⁵. This will require simultaneous genetic testing and morphological characterisation¹⁴. Conservation Actions Proposed Develop techniques for the identification of A. wyvilliana, A. platyrhynchos and hybrids¹⁵. Determine range, behaviour, and abundance of A. wyvilliana, A. platyrhynchos and hybrids¹⁵. Estimate the extent of hybridisation¹⁵. Vigorously and humanely control A. platyrhynchos and hybrids^1,5,9,14,15. Restore wetlands¹. Control predators where feasible^2,10,14. Raise awareness amongst policy makers and the public of the threat from A. platyrhynchos and need for control^14,15. Prevent imports and releases of A. platyrhynchos and closely related species^14,15. Protect and manage core and supporting wetlands¹⁴. Conduct an environmental education programme for landowners and land managers¹⁴. Control invasive plants¹⁴. Identify sites for reintroduction on Maui and Moloka`i¹⁴. Assess the future use of captive breeding and translocation¹⁴. Reintroduce either captive-bred or translocated birds to protected and managed sites on Maui and Moloka`i and monitor these new populations¹⁴.

Conservation Actions:

Conservation Actions Underway
On Kaua`i, the Hanalei National Wildlife Refuge is an important area for the species, especially in winter¹². The species was reintroduced to O`ahu through the release of 326 captive-bred birds between 1958 and 1982¹⁴; in 1989, fewer than 12 captive-bred birds were released on Maui; and between 1976 and 1982, the species was reestablished on Hawai`i also through the release of captive-bred birds¹⁴. In the late 1980s, the importation of A. platyrhynchos was restricted by the state, with exceptions only for research and exhibition¹⁵. In 2002, the department of agriculture placed an embargo on all birds shipped to the Hawaiian islands, to protect the public from West Nile Virus. Research is being carried out to develop techniques for the identification of hybrids¹⁵. This will require simultaneous genetic testing and morphological characterisation¹⁴.

Conservation Actions Proposed
Develop techniques for the identification of A. wyvilliana, A. platyrhynchos and hybrids¹⁵. Determine range, behaviour, and abundance of A. wyvilliana, A. platyrhynchos and hybrids¹⁵. Estimate the extent of hybridisation¹⁵. Vigorously and humanely control A. platyrhynchos and hybrids^1,5,9,14,15. Restore wetlands¹. Control predators where feasible^2,10,14. Raise awareness amongst policy makers and the public of the threat from A. platyrhynchos and need for control^14,15. Prevent imports and releases of A. platyrhynchos and closely related species^14,15. Protect and manage core and supporting wetlands¹⁴. Conduct an environmental education programme for landowners and land managers¹⁴. Control invasive plants¹⁴. Identify sites for reintroduction on Maui and Moloka`i¹⁴. Assess the future use of captive breeding and translocation¹⁴. Reintroduce either captive-bred or translocated birds to protected and managed sites on Maui and Moloka`i and monitor these new populations¹⁴.

Citation:	BirdLife International 2011. Anas wyvilliana. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 08 February 2012.
Disclaimer:	To make use of this information, please check the <Terms of Use>.
Feedback:	If you see any errors or have any questions or suggestions on what is shown on this page, please fill in the feedback form so that we can correct or extend the information provided