The 134 Laysan ducks who were found dead on Midway Atoll National Wildlife Refuge died from avian botulism, according to the National Wildlife Health Center.

The toxin was found in all eight samples taken from the refuge in Papahanaumokuakea Marine National Monument. The wildlife health center is in the process of draining the catchment wetland where most of the deaths have occurred, according to the U.S. Fish and Wildlife Service.

Avian botulism is a different than botulism that occurs in humans. It does not spread to humans and is caused by a toxin produced by a widespread bacterium that breeds in warm stagnant water.

The first dead ducks were discovered on Aug. 10. The population at Midway is about 200 birds Laysan Island, where a larger population of birds can be found, is more than 100 nautical miles away. There is no risk of Midway's bout of avian botulism affecting the Laysan population, scientists say.

The Papahanaumokuakea Marine National Monument is administered jointly by the Department of Commerce, the Department of the Interior and the state of Hawai'i. The 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 the Northwestern Hawaiian Islands State Marine Refuge.