A revised plan that describes the actions needed to recover four species of endangered Hawaiian waterbirds was released today by the U.S. Fish and Wildlife Service. This second revision updates earlier recovery plans issued in 1978 and 1985 and provides detailed guidance for numerous public and private entities engaged in the conservation of the Hawaiian duck or koloa maoli, Hawaiian coot or ‘alae ke‘oke‘o, Hawaiian common moorhen or ‘alae ‘ula, and Hawaiian stilt or ae‘o.
“These four species, found only in Hawai‘i, were once found in a variety of wetland habitats on all the main Hawaiian Islands, except Lana‘i and Kaho‘olawe,” said Loyal Mehrhoff, field supervisor for the Fish and Wildlife Service’s Pacific Islands Fish and Wildlife Office. “Loss of wetland habitat was a primary cause for the species’ declines, but predation by introduced animals is currently the main threat to the coot, moorhen, stilt, and also impacts the Hawaiian duck. Thanks to the involvement and commitment of many cooperators in Hawai‘i, Hawaiian waterbirds are currently doing better.”
Five broad objectives are outlined in the second revised plan:
- increase population numbers of each species to suitable statewide numbers;
- establish multiple, self-sustaining breeding populations throughout each species’ historical range;
- establish and protect a network of both core and supporting wetlands that are managed as habitat suitable for waterbirds;
- eliminate or control the threats posed by introduced predators, avian diseases, and contaminants;
- for the Hawaiian duck, remove the threat of hybridization with feral mallards.
Specific criteria necessary for either downlisting (changing from endangered to threatened) or delisting (removing from the list of threatened and endangered species) each of the four waterbird species are identified under these objectives.
Many factors contributed to the decline of waterbirds, including predation by introduced animals (e.g., mongoose, dogs, cats, and bull frogs), loss of wetlands, alteration of habitat by invasive nonnative plants, disease, and possibly environmental contaminants. Hunting in the late 1800s and early 1900s also took a heavy toll on Hawaiian duck populations and to a lesser extent on populations of the other three endemic waterbirds.
Based on data from the State’s biannual waterbird counts, none of these species consistently number more than 2,000 individuals, with the exception of the Hawaiian coot. Population estimates tend to fluctuate depending on factors such as rainfall amount. Scientists have found it difficult to determine the status of the Hawaiian duck and Hawaiian common moorhen due to the difficulty of distinguishing between Hawaiian ducks, feral mallards, and hybrids, and the secretive nature of the Hawaiian common moorhen and its use of densely vegetated wetland areas. However, trend data collected over the past three decades show that the Hawaiian coot, Hawaiian common moorhen, and Hawaiian stilt populations are either stable or increasing.
The Hawaiian duck is a small brown duck closely related to the mallard. Both sexes are mottled brown with an emerald green to blue speculum (brightly colored areas on the wings) and similar in appearance to a female mallard. Hawaiian ducks are currently found on the islands of Kaua‘i, Ni‘ihau, O‘ahu, Maui, and Hawai‘i. The most serious threat to the Hawaiian duck is cross breeding or hybridization with feral mallards.
The Hawaiian coot is slate-gray in color, with white undertail feathers and a bulbous frontal shield above its usually all white bill. A small percentage of Hawaiian coots have a red shield and black bill similar to their mainland relative, the American coot. Male and female Hawaiian coots are similar in color and have large feet with lobed toes (unlike ducks which have webbed feet). Hawaiian coots currently inhabit all of the main Hawaiian Islands except Kaho‘olawe.
Hawaiian common moorhens are similar to the Hawaiian coot, black above and slate blue below, but they are smaller, have a red shield over their red and yellow bill, and a white flank stripe. In addition, they have very long and slender toes that allow them to walk on floating wetland plants. The sexes are similar in appearance. Hawaiian common moorhens have the smallest distribution of these four species and occur only on the islands of Kaua‘i and O‘ahu.
The black and white Hawaiian stilt is a slender wading bird with distinctive long, pink legs and is considered a separate subspecies of the black-necked stilt found on mainland North America. The Hawaiian stilt differs from North American black-necked stilts in that its black coloration extends lower on the forehead as well as around the sides of the
neck, and by having a longer bill and longer legs. The sexes are distinguished by the color of the back feathers (brownish in females, black in males) as well as voice (females have a lower voice). Hawaiian stilts are currently found on all the main Hawaiian Islands except Kaho‘olawe.
Copies of the final second revised recovery plan are available on the Service’s website at http://www.fws.gov/pacificislands/ or by calling the Service’s Honolulu office at 808 792 9400. Written comments may be submitted to the Field Supervisor, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Blvd., Room 3-122, Box 50088, Honolulu, HI 96850.