Wildlife officials from Midway Atoll National Wildlife Refuge and the National Wildlife Health Center Honolulu Field Station are investigating the deaths over the last several days of more than 100 endangered Laysan ducks on the Refuge in Papahanaumokuakea Marine National Monument. Although no definitive cause has been identified at this time, avian botulism is suspected. Managers are taking steps to control the outbreak, and the number of deaths per day is now declining.
"Although we suspect avian botulism, we will not have a confirmed diagnosis until next week," explained Matt Brown, acting refuge manager at Midway. "In the meantime, as recommended in these cases, we have added large amounts of fresh water to many of the wetland seeps where dead birds have been found in order to reduce stagnation. Dead birds are being collected and burned to reduce further spread of potential disease."
Using necessary safeguards, a number of carcasses are being shipped to the National Wildlife Health Center Honolulu Field Station for further analysis on todays flight from Midway. The remote refuge is serviced by only three flights per month; todays flight is the first one since the outbreak occurred. Samples will be sent on to the National Wildlife Health Center in Madison, Wisconsin to confirm whether avian botulism is a cause of the die-off.
The first dead duck was discovered on August 10; surveys of all seeps on the atoll are being conducted each day. As of today, a total of 106 adult and adolescent birds have been found dead. The population level at Midway was estimated at 200 birds in December 2007, but successful fledging this year almost doubled that population level. The remaining population on Laysan Island, also in the Monument, roughly numbers 600 Laysan ducks.
"We are naturally upset by this loss, which further underscores the need to have Laysan ducks at more than one location in the Hawaiian Islands," Brown said. "We sincerely hope we have seen the worst of this outbreak, and that our Midway population of Laysan ducks will rebound quickly."
In 2004 and 2005, 42 wild mostly juvenile ducks made a 750-mile Pacific voyage and were released at Midway Atoll as a conservation action to increase the rare ducks geographic distribution and reduce its risk of extinction. The endangered Laysan duck is considered the rarest native waterfowl in the United States and occurs only within the Northwestern Hawaiian Islands Papahanaumokuakea Marine National Monument. Laysan ducks were once widespread across the Hawaiian Islands, but by 1860, they were extirpated from all but Laysan Island, part of the Hawaiian Islands National Wildlife Refuge.
Papahanaumokuakea Marine National Monument is administered jointly by three co-trustees - the Department of Commerce, Department of the Interior and the State of Hawaii - and represents a cooperative conservation approach to protecting the entire ecosystem. Co-trustee agencies in cooperation with the Office of Hawaiian Affairs manage the monument through the Monument Management Board. The Monument area includes the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve, Midway Atoll National Wildlife Refuge/Battle of Midway National Memorial, Hawaiian Islands National Wildlife Refuge, Kure Atoll Wildlife Sanctuary, and Northwestern Hawaiian Islands State Marine Refuge.
