photo credit: Eric VanderWerf

Hawaii Conservation Alliance Position Statement Introduced Mallards (Anas platyrhynchos) are driving the genetic extinction of Hawaii’s endangered Koloa maoli (Hawaiian Duck, A. wyvilliana). Hybridization with feral Mallards (domestics reproducing in the wild) is currently the most serious threat to Koloa. Public outreach, in conjunction with feral Mallard control, is essential. Governmental support to strengthen and enforce quarantine laws and regulate instate breeding and commerce is crucial to stopping the sources of feral Mallards and closely-related nonnative ducks. We must act now to prevent loss of another Hawaiian bird and secure a future for our Koloa maoli.

In September, 2008, the Hawai‘i Conservation Alliance published a position paper titled The Feral Mallard Threat To Hawai`i’s Native Duck to raise awareness about the serious threat to the continued existence of Hawai‘i's native duck, the Koloa Maoli. Here we present some highlights from the HCA paper.   Koloa Maoli – Hawai‘i’s Endangered Native Duck Koloa maoli (or simply Koloa) are small, native ducks that are rarely seen except by those who seek them in remote wetlands and mountain streams. They are shy creatures whose numbers have declined dramatically due to hybridization with feral Mallards, introduced predators, and habitat loss. Once found throughout the main Hawaiian Islands, today Koloa are found mostly in wetland habitats on Kaua‘i, Ni‘ihau, and Hawai‘i. In the Ka‘u region of Hawai‘i, these native birds figure in the story of the legendary blind chief Imaikalani who had two Koloa guardians that warned him when anyone was approaching.   photo credit: Eric VanderWerf   The Feral Mallard Threat Mallard ducks were brought to Hawai‘i in the mid-1800’s for hunting and domestic uses. Mallards were released or escaped into the wild and began breeding with wild Koloa, producing fertile, hybrid offspring. Over generations, the continued interbreeding among hybrids, feral Mallards, and Koloa has lead to the dramatic loss of wild Koloa. This “unnatural” hybridization has been aided by habitat modifications that bring the wild Koloa into contact with feral Mallards and hybrids. Although small numbers of migratory Mallards also occur in Hawai‘i, they arrive and depart with other migratory ducks that call Hawai‘i home during their nonbreeding season and are not believed to pose a threat to Koloa. However, feral Mallards directly threaten Koloa with extinction not only due to the hybridization but because they can negate all other efforts to help Koloa.   Domestic Mallards continue to be used on a small scale for apple snail control in taro patches, weed control, and food production. The HCA supports responsible use of domestic ducks in agriculture. However, increasing numbers of abandoned domestic ducks (feral ducks) point to the need for stronger regulatory controls on domestic ducks within Hawai‘i.

More information on Koloa maoli   Web sites U.S. Fish & Wildlife Service Malama Hawaii   Download:   Hawaiian Duck’s Future Threatened by Feral Mallards USGS Fact Sheet (PDF)   Conservation of Hawaii Duck: Research and Management Needs Uyehara et al.

Part of the solution is to reduce the population of feral Mallards so they do not interbreed with Koloa. This requires trapping and killing feral ducks. Some people may find this upsetting and question why hybrid birds are bad. We believe, however, that when given a choice between feral Mallards/hybrids or wild Koloa, an aware public will choose the Koloa. The simple truth is we can’t have both – the fate of a unique Hawaiian species is at stake.

• Promote responsible domestic duck ownership to prevent releases or escapes of domesticated Mallards, including barnyard ducks;
• Support voluntary removal of domesticated Mallards from private property;
• Develop and implement a plan for humane removal of feral Mallards and Mallard/Koloa hybrids from the wild;
• Prevent habitat modifications that further give feral Mallards the competing edge; and
• Enforce quarantine laws that prohibit the importation to Hawai‘i of Mallards and related ducks.