More than 80,000 birds have died over the past two and half months at a network of wildlife refuges on the Oregon-California border, the largest outbreak in the recorded history of the refuges in a region roiled by drought and water uncertainty.
The deaths, linked to a rare combination of botulism and avian flu, increased sharply since the end of August when about 5,000 dead birds had been counted.
And because botulism thrives in warm, stagnant water, many more birds are likely to die before the rainy season and cold temperatures begin, said John Vradenburg, supervisory biologist at the refuge complex.
“Due to the current temperature patterns, we see little sign of relief in the forecast until early to mid-October,” Vradenburg told The Oregonian/OregonLive.
Most of the birds have died at the Tule Lake National Wildlife Refuge, one of the refuges in the network. The refuge staff must pick up the dead birds because leaving them in the water could worsen the outbreak, spreading more disease.
The outbreak has surpassed the outbreak of 2020, when at least 60,000 waterfowl and shorebirds died of botulism at the refuges. It comes at a time when the wetlands are teeming with birds, including ducks, geese, grebes and shorebirds, Vradenburg said.
Virus-caused avian flu has been on the rise in recent years, killing poultry and wild birds alike. Botulism, which paralyzes birds from the bottom up until they are unable to fly and then to breathe, is caused by a natural toxin produced by soil-dwelling bacteria, but typically doesn’t lead to large-scale die-offs.
But as wetland habitat continues to shrink, forcing birds into smaller patches of water, and climate change dries up what’s left of the habitat, the toxin has infected many more birds. Competition for water in the Klamath Basin makes the situation worse.
The six refuges, known collectively as the Klamath Basin National Wildlife Refuge Complex, contain the largest wetland network west of the Mississippi River. They’re a stopping point for 80% of the birds that migrate on the Pacific Flyway, a major north-south path for a diverse number of migratory birds in the Americas.
Last month, conservation groups called for the Klamath Project to release more water to the refuge complex and the U.S. Bureau of Reclamation delivered some of the water – but it was not enough to slow down the outbreak, according to the Bird Alliance of Oregon.
The group says long-term solutions are needed, especially as climate change will lead to even more frequent, longer high heat conditions.
“The devastation happening here due to the botulism outbreak will have long lasting impacts across the entire West Coast,” said Teresa Wicks, a Bird Alliance biologist who visited the refuge this summer.
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