Botulism strikes ducks in Horicon

(Published Thursday, August 4, 2005)

Associated Press

MILWAUKEE - An outbreak of botulism at Horicon National Wildlife Refuge in Dodge County has killed more than 1,000 ducks this summer, the largest die-off at the refuge since the 1970s.

The loss is about a tenth of the resident mallard population.

An official said ducks are killed every year at the refuge because of avian botulism.

But this year, a combination of hot weather and low water levels because of a water drawdown combined to cause even more deaths on the 20,000-acre federal section of the refuge, said Wendy Woyczik, a biologist for the refuge.

She said the mallards are eating maggots that feed on rotting catfish that are dying because of low water levels in the refuge. The maggots are akin to "toxic pellets" filled with a natural bacterium in the soil that becomes toxic because of high heat and decaying organic matter like fish and plants.

The southern, state-operated section of the refuge, which is about 11,000 acres, has not been affected, officials said.