Roughly 10,000 birds, mostly snow geese, have died of avian cholera on and near the water-starved Lower Klamath and Tule Lake national wildlife refuges.

Limited water deliveries to the refuges, combined with large bird migrations, are blamed for the cholera outbreak, said Ron Cole, the Klamath Basin National Wildlife Refuges Complex manager.

He said limited water deliveries to Lower Klamath last fall and this winter have dried up about half of the refuge’s wetlands. In turn, about 2 million birds, including large numbers of migrating pintails and Arctic nesting geese, are concentrated in smaller areas.

“When you concentrate that many birds on about half of the available wetlands, you develop a recipe for an avian cholera outbreak,” Cole said, noting the bacteria that causes avian cholera spreads more rapidly in heavy concentrations of birds.

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