An updated draft recovery plan for Hawai'i's endangered waterbirds says that the koloa maoli or Hawaiian duck's greatest threat is from interbreeding with its cousin, the mallard.

The koloa and mallard are closely related — close enough to produce hybrid offspring — but the koloa is considerably less flashy in color, with both males and females adorned in mottled browns. There are 2,000 or fewer koloa left in the state, with small populations on Ni'ihau, Kaua'i, O'ahu, Maui and Hawai'i.

Loss of wetland habitat is a significant issue for the koloa's population decline as well as that for three other endangered waterbirds addressed by the recovery plan: the Hawaiian coot or 'alae ke'oke'o, Hawaiian moorhen or 'alae 'ula, and the Hawaiian stilt or ae'o. For the coot, moorhen and stilt, however, perhaps the larger threat is from the animals and their nests being attacked by introduced animals, such as mongooses, dogs and cats.

The plan proposes a set of wetlands across the state that are managed as habitat for the birds, along with other suggestions designed to increase populations of the birds so they can be removed from the endangered species list.

The updated draft recovery plan is available on the Web at pacificislands.fws.gov. Or for a copy, call the Fish and Wildlife Service Honolulu office at 792-9400. The agency will accept written comments on the plan through Oct. 24 addressed to Field Supervisor, Pacific Islands Fish and Wildlife Office, 300 Ala Moana, Room 3-122, Box 50088, Honolulu, HI 96850.