Biologists at the Klamath Basin National Wildlife Refuge Complex have been collecting around 1,000 dead birds each day in recent weeks, plucking them out of the marshy waterways of the Tule Lake National Wildlife Refuge, and bringing them to refuge facilities where they鈥檙e disposed of in incinerators.
Live birds are being captured and brought to a makeshift bird hospital run by the nonprofit Bird Ally X. There, wildlife rehabilitators provide supportive care to the birds until they can regain their strength and the botulism toxin dissipates from their bodies.
鈥淚t鈥檚 kind of like a wildfire,鈥� said John Vradenburg, supervisory biologist for the refuge complex. 鈥淲hen these events start, they can get to be really widespread. Our job is to contain it. The tools that help us contain it is getting that water moving and flowing across as much of the wetland as possible.鈥�
Botulism is produced by a soil bacteria that flourishes in stagnant, warm water. In waterfowl, the neuromuscular illness can lead to birds drowning when they鈥檙e unable to hold their heads up.
Vradenburg said the outbreak has shrunk from an area of around 2,000 acres to a current size of about 500 acres. The high mortality numbers are because of the large number of migratory birds that are now stopping off on the refuge complex during their fall migration along the Pacific Flyway.
鈥淲e tend to see small botulism outbreaks every year,鈥� he said. 鈥淭hese big ones tend to be when we don't get the weather setting in that can stop the cycle.鈥�
Vradenburg said temperatures at the refuges have not dipped to their usual freezing levels yet this year, which is prolonging the presence of the toxin. The outbreak should be shut down within 3-4 days of cold nighttime temperatures.
Arcata-based Bird Ally X is operating the field hospital or 鈥渂ird MASH unit鈥� in the refuge maintenance yard. They鈥檙e rehabilitating the long-billed dowitchers, black-necked stilts, northern pintails and American widgeons that refuge staff bring in each day. Much of the group鈥檚 treatment involves stress reduction of the wild birds, while providing them with oral fluids and vitamins to help them recover faster.
鈥淲hile the botulism bacteria itself is natural, the waterways here are not natural anymore,鈥� said Bird Ally X Co-Founder January Bill, who has been working at the field hospital. 鈥淭he amount of water on these wetlands aren鈥檛 natural, so it鈥檚 creating these unnatural outbreaks.鈥�
The drought-stricken Klamath Basin is a region where there鈥檚 a variety of demands on water including agriculture and federally mandated allocations for endangered species in Upper Klamath Lake as well as down the Klamath River. That means the wildlife refuge complex is routinely denied the abundance of water that led to its 1908 designation as the first waterfowl refuge in the United States.
In mid-August, advocacy from a consortium of conservation groups led to extra water being diverted to the refuge by federal managers at the Bureau of Reclamation. According to Vradenburg, that decision was critical to preventing the outbreak from growing even bigger.
鈥淓ven though the [bird mortality] numbers seem high, it made a significant impact in the trajectory that this thing was going. It could have been far worse,鈥� Vradenburg said.
The Bureau of Reclamation did not provide a comment about the outbreak response by deadline.
While Vradenburg鈥檚 estimate of 45,000-55,000 birds dying may seem dramatic, he said, it鈥檚 worth putting in the context of millions of birds migrating on the Pacific Flyway between North and South America each year. And if there鈥檚 a silver lining, he said, it鈥檚 that the waterfowl that breed locally in California weren't dramatically impacted this year. That population was hit hard recently after a devastating botulism outbreak in 2020 that killed 60,000 birds, plus four subsequent years of drought.
Now, conservationists are hoping for freezing temperatures to kill the toxin and end the outbreak. With temperatures dropping to the high 30s in the coming days, that frost may not be far off.
鈥淭he best thing that can happen for us right now is for things to start getting cold,鈥� Vradenburg said.
