The carcasses were piling up well before the migration was in full swing. By Oct. 1, officials at Tule Lake National Wildlife Refuge had already scooped up 10,000 dead ducks and geese, all victims of avian botulism. Refuge managers expected this outbreak to continue, thanks to the severe drought gripping much of California. The lack of water is concentrating waterfowl into small areas, which creates the perfect conditions for a massive outbreak. Once the disease takes hold, it can continue to infect birds that come in contact with diseased corpses or other infected ducks. The outlook is bleak for Tule Lake, which holds tens of thousands of waterfowl during peak migration. It's the only refuge in the Klamath Basin that has water. Even if the botulism outbreak does subside, biologists fear a different disease: avian cholera. It usually works its way through waterfowl during the winter. A cholera outbreak killed 10,000 birds in 2012 on Tule Lake NWR. There were no more official death counts at press time, but we hope to provide an update later this year.