Final Comprehensive Conservation Plan - U.S. Fish and Wildlife ...

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
koloa maoli exists on Kaua„i, with repatriated populations on O„ahu, Hawai„i, and Maui (Pratt et al.
1987, Engilis et al. 2002, Hawaii Audubon Society 2005). The current Statewide population of pure
koloa maoli is estimated at 2,200 birds; approximately 200 individuals occur on the island of Hawai„i
and the remainder reside on Kaua„i. The populations on O„ahu and Maui are suspected to largely
consist of hybrids – a crossbreed between the koloa maoli and mallard ducks. Estimated koloa maoli
counts on these islands are 300 and 50 birds, respectively (Engilis et al. 2002, USFWS 2005a).
Genetic studies of the species have suggested that a pure, intact population of koloa maoli may not
exist on O„ahu (Browne et al. 1993). Although hybridization has been documented to occur on
Hawai„i‟s lowland wetlands and remains a threat on Kaua„i, the koloa maoli population on these two
islands appear to be stable (Engilis et al. 2002).
The Hawai„i Island population was reestablished between 1976-1982, when captive-bred birds were
released in the Kohala Mountain (Engilis et al. 2002). Populations currently occur in the stock ponds
in the Kohala Mountains; stream habitats of Pololū, Waimanu, and Waipio Valleys; and in the stock
ponds and larger montane streams on Mauna Kea. On the HFU, this species inhabits and breeds in
streams and ponds (USFWS 2002a, USFWS 2005a, Jeffrey, pers. comm.). Due to the lack of surface
water at the KFU, this species is not expected to occur within the unit boundaries.
The koloa maoli uses a wide array of habitat types such as natural and manmade lowland wetlands,
flooded grasslands, river valleys, mountain streams, montane pools, forest swamplands, aquaculture
ponds, and agricultural areas. The diet of koloa maoli consists of aquatic invertebrates, aquatic
plants, seeds, grains, green algae, aquatic mollusks, crustaceans, and tadpoles (Engilis et al. 2002,
Hawaii Audubon Society 2005, USFWS 2005a). The majority of nesting occurs from March-June
with broods observed year-round. Nests are placed in dense shoreline vegetation of small ponds,
streams, ditches, and reservoirs. Bunch-type grasses, rhizominous ferns, and shrubs are typically used
at nesting sites (Engilis et al. 2002). On the island of Hawai„i, successful breeding in the wild has
been documented in the Kohala Mountains and at HFU (USFWS 2005a).
Although the USFWS Recovery Plan for Hawaiian Waterbirds lists the koloa maoli as having a high
potential for recovery, the species has a high degree of threat due to hybridization with mallard ducks
(USFWS 2005a). Hybridization with mallards is currently the greatest threat to this species‟
continued existence (Engilis et al. 2002, Uyehara et al. 2007). In addition to hybridization concerns,
other hazards exist for koloa maoli. Known predators of eggs and chicks include mongooses, cats,
dogs, and possibly rats. „Auku„u, largemouth bass, and American bullfrogs have been observed to
take ducklings. Avian diseases are another threat to koloa maoli with outbreaks of avian botulism
occurring annually throughout the State (Engilis et al. 2002).
4.6.3 ‘Alae ke‘oke‘o (Fulica alai)
The „alae ke„oke„o, or Hawaiian coot, is a small waterbird endemic to Hawai„i that is federally listed
as endangered. Adult males and females have a black head, a slate gray body with white undertail
feathers, and a prominent white frontal shield and bill; feet are lobed rather than webbed and are
greenish-gray. Life-history and breeding biology are poorly known. „Alae ke„oke„o use freshwater
and brackish wetlands, which can include agricultural wetlands and aquaculture ponds. They are
generalists and feed on land, from the surface of the water, or will dive. They will also graze on grass
adjacent to wetlands. They will travel long distances if local food sources (e.g., seeds, leaves, snails,
crustaceans, insects, small fish, etc.) are not available. Appropriate water levels are critical to nesting
Chapter 4. Refuge Biology and Habitats 4-43