KLAMATH COUNTY, Ore. – Refuge staff collected 500 dead birds from Sump1A, the largest water body in the Tule Lake National Wildlife Refuge in far Northern California. The supervisory biologist at the Klamath Basin National Wildlife Refuge Complex, John Vradenburg, suspects a dual outbreak of botulism and highly pathogenic avian influenza are behind the birds dying as these were found in the refuges.