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| Subspecies: | Unknown |
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| Est. World Population: | 700-999 |
| CITES Status: | NOT LISTED |
| IUCN Status: | Vulnerable |
| U.S. ESA Status: | NOT LISTED |
| Body Length: | |
| Tail Length: | |
| Shoulder Height: | |
| Weight: | |
| Top Speed: | |
| Jumping Ability: | (Horizontal) |
| Life Span: | in the Wild |
| Life Span: | in Captivity |
| Sexual Maturity: | (Females) |
| Sexual Maturity: | (Males) |
| Litter Size: | |
| Gestation Period: | |
Habitat:
It inhabits wetlands, including coastal ponds, lakes, swamps, flooded grasslands, mountain streams, anthropogenic water-bodies and occasionally boggy forests (Todd 1996, T. C. Telfer in litt. 1999). Breeding occurs year-round, with the peak nesting season between September and May (Malachowski et al. 2019). It is an opportunistic feeder, taking invertebrates, seeds and plant matter (USFWS 2005).
Range:
Anas wyvilliana was once an inhabitant of all the main Hawaiian Islands (U.S.A.) except Lana'i and Kaho'olawe (USFWS 2005), but is now restricted to Kaua'i and Ni'ihau (Wells et al. 2019, Malachowski 2020).
Conservation:
Conservation Actions Underway
On Kaua'i, the Hanalei National Wildlife Refuge is an important area for the species, especially in winter (Todd 1996). The species was reintroduced to O'ahu through the release of 326 captive-bred birds between 1958 and 1982 (USFWS 2005); in 1989, fewer than 12 captive-bred birds were released on Maui; and between 1976 and 1982, the species was reestablished on the Big Island also through the release of captive-bred birds (USFWS 2005). However, recent research on the population genetics and movement ecology of the species indicates that only individuals on Kaua'i and Ni'ihau can now be considered pure owing to extensive hybridisation with A. platyrhynchos (Wells et al. 2019, Malachowski 2020). In the late 1980s, the importation of A. platyrhynchos was restricted by the state, with exceptions only for research and exhibition (Uyehara et al. 2007). Efforts are ongoing to develop a key to distinguish between hybrids and pure individuals (USFWS 2021). 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. Predator control and habitat restoration is ongoing on Kaua'i (VanderWerf 2012). There is some monitoring of wetland areas and removal of carcasses for botulism outbreaks (USFWS 2021).
Conservation Actions Proposed
Continue annual statewide waterbird counts (USFWS 2021). Research and survey montane stream habitat for the species (USFWS 2021). Protect and manage core and supporting wetlands. Develop and implement a statewide humane feral mallard and hybrid duck removal plan (USFWS 2021). Conduct a public information and awareness program regarding the hybridisation problem (USFWS 2021). Strengthen quarantine rules and regulations to restrict instate production and commerce of mallards and closely related ducks (USFWS 2021). Continue predator control and implement improved methods as they become available (USFWS 2021). Expand predator control outside of Hanalei Wildlife Refuge (Malachowski 2020). Remove nonnative, invasive plants and improve altered wetland hydrology as appropriate (USFWS 2021). Research and develop new tools to prevent botulism related mortality (USFWS 2021). Assess the future use of captive breeding and translocation (USFWS 2011).
On Kaua'i, the Hanalei National Wildlife Refuge is an important area for the species, especially in winter (Todd 1996). The species was reintroduced to O'ahu through the release of 326 captive-bred birds between 1958 and 1982 (USFWS 2005); in 1989, fewer than 12 captive-bred birds were released on Maui; and between 1976 and 1982, the species was reestablished on the Big Island also through the release of captive-bred birds (USFWS 2005). However, recent research on the population genetics and movement ecology of the species indicates that only individuals on Kaua'i and Ni'ihau can now be considered pure owing to extensive hybridisation with A. platyrhynchos (Wells et al. 2019, Malachowski 2020). In the late 1980s, the importation of A. platyrhynchos was restricted by the state, with exceptions only for research and exhibition (Uyehara et al. 2007). Efforts are ongoing to develop a key to distinguish between hybrids and pure individuals (USFWS 2021). 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. Predator control and habitat restoration is ongoing on Kaua'i (VanderWerf 2012). There is some monitoring of wetland areas and removal of carcasses for botulism outbreaks (USFWS 2021).
Conservation Actions Proposed
Continue annual statewide waterbird counts (USFWS 2021). Research and survey montane stream habitat for the species (USFWS 2021). Protect and manage core and supporting wetlands. Develop and implement a statewide humane feral mallard and hybrid duck removal plan (USFWS 2021). Conduct a public information and awareness program regarding the hybridisation problem (USFWS 2021). Strengthen quarantine rules and regulations to restrict instate production and commerce of mallards and closely related ducks (USFWS 2021). Continue predator control and implement improved methods as they become available (USFWS 2021). Expand predator control outside of Hanalei Wildlife Refuge (Malachowski 2020). Remove nonnative, invasive plants and improve altered wetland hydrology as appropriate (USFWS 2021). Research and develop new tools to prevent botulism related mortality (USFWS 2021). Assess the future use of captive breeding and translocation (USFWS 2011).