Monday made four straight days that state wildlife officials had not found any dead or sick birds with botulism at Kanaha Pond, signaling an end to the outbreak that infected 92 endangered birds and killed 83.
"Hopefully, it's over," said state Forestry and Wildlife Division wildlife biologist Fern Duvall on Monday.
The first birds afflicted with botulism at the Kahului pond near the airport were detected on June 12. Since then, wildlife officials have been "slugging through the muck" every day to find afflicted birds and carcasses, said Duvall. The sick birds were given an antitoxin in hopes of saving them; the dead birds were removed to "break the chain reaction" of transmission of the disease through the food chain. Maggots from the inflected birds that provide a high dose of the paralytic toxin when consumed were of particular concern.
Endangered Hawaiian coots swim in Kanaha Pond last month, during an outbreak of botulism there. State wildlife officials believe they have the outbreak under control, finding no sick or dead birds in the pond for four consecutive days.
The Maui News / MATTHEW THAYER photo
Of the 92 birds infected, 52 were Hawaiian stilts, 11 were Hawaiian coots and 29 were Hawaiian ducks - all endangered birds. In addition, 14 Hawaiian stilt nests were found abandoned with 42 eggs lost, said Duvall. Noting that it is nesting time for the stilts, Duvall said that it was unlikely that the lost eggs could be recouped this season. Stilts eggs have a high hatchability rate; it was likely that almost all of the 42 eggs would have hatched, he said.
Of the 92 birds, 20 were found alive. Of those, nine birds survived and were released, he said.
The toxin in the botulism bacteria has a paralytic effect, blocking the nerve endings. Birds die from respiratory arrest or are unable to hold up their necks, sometimes referred to as "limberneck," and drown in the water.
Botulism is a natural toxin produced by a bacteria commonly found in soil. The avian disease - which is the same bacteria but a different strain as the human form associated with improperly canned food - thrives in low- or no-oxygen water conditions. The disease is transmitted through the food system to birds.
Wildlife officials will continue to have "heightened surveillance" at the pond for a week, but they will not have to slog their way through the water where some areas are like "quicksand," said Duvall. Since the discovery of the first infected bird, they have been in the pond every day.
Duvall said earlier that they do not know how the toxin infected birds in the pond.
* Lee Imada can be reached at firstname.lastname@example.org.