Drought a key factor in duck refuge die-off

GRANTS PASS, Ore. – The drought that has forced irrigation shutoffs at cattle ranches in the upper Klamath Basin is also causing hardship for waterfowl on national wildlife refuges in the region.

Thousands of ducks are dying from a disease called avian botulism on the Tule Lake National Wildlife Refuge near Tule Lake, Calif., due to overcrowded marshes.

While the Tule Lake refuge gets water running off a federal irrigation project that’s getting water, current management plans allow none this summer for the Lower Klamath National Wildlife Refuge, which is practically dry.

That leads to overcrowding on the marshes at Tule Lake, which promotes the spread of the disease, refuge biologist Dave Mauser said. The 13,000 acres of marsh is supporting some 150,000 birds. So far volunteers have picked up 4,500 dead birds, most of them mallards and other kinds of ducks, in an effort to stop the spread of the disease. Mauser estimates the disease has killed about 9,000, putting this year on track to be one of the worst this decade.

The ducks can’t fly somewhere else, because they are molting and have lost their flight feathers, leaving them stranded for a month, he added.

The refuges are a key stop on the Pacific Flyway, and the outlook for this fall is not good, Mauser said. Normally, Lower Klamath would have 20,000 acres flooded now, with water to flood several thousand acres more this fall, after irrigation season is done. But overall the marsh will be about half of normal, and drought is drying up marshes up and down the West Coast, Mauser said. Birds that survive the outbreak may well spread it to other marshes once they embark on their fall migration.

“It’s frustrating,” Mauser said. “The way water policies are, we’re last in line for water.”

Drought this year has reverberated through the basin. The Klamath Tribes are exercising newly recognized senior water rights to protect fish on rivers on former reservation lands in the upper basin. That has forced irrigation shutoffs to ranches drawing water for cattle pasture. Meanwhile, a federal irrigation project is getting most of the water it needs for farms. But that has left none for Lower Klamath refuge, which is at the end of the line. Meanwhile, water that would normally go to farms in central California is being released to keep Klamath River salmon from dying.

Botulism is a toxic bacterium that grows in low oxygen conditions on protein, such as dead fish or birds. Maggots feeding on the rotting flesh take in the toxin, and ducks eating the maggots get sick and die. This strain of botulism does not affect humans, Mauser said.