YREKA (CBS / AP) — The U.S. Fish and Wildlife Service is blaming a lack of water for a massive die-off of migrating birds at a wildlife refuge on the Northern California-Oregon border.
Up to 20,000 birds have died at the Lower Klamath National Wildlife Refuge since February — the worst die-off in the region in about a decade.
Fish and Wildlife spokesman Matthew Baun says only about half the refuge was flooded this year. That contributed to a higher concentration of the birds, increasing disease transmission.
The dead have been found to be suffering from avian cholera.
Environmentalists say the die-off shows water resources are not being properly managed.
(Copyright 2012 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)