State wildlife officials are trying to learn how two endangered California condors died after the birds were found last month in water tanks used by firefighters in California's Central Valley.
The bodies have been sent to a forensics lab in Oregon to try to determine the cause of death, the Los Angeles Times reported Sunday. They were discovered last month in separate water tanks in the Tehachapi area, about 100 miles north of Los Angeles.
Because the condors number only about 100 in the wild, losing two in the same month is significant.
The first bird was discovered Oct. 2 after a tracking transmitter that wildlife authorities had attached to it quit working.
Kern County firefighters taking part in "The Great California Shakeout" earthquake preparedness drill found the second one on Oct. 17.
"They both appeared to be in the tank for a number of days," said Joseph Brandt, supervising wildlife biologist for the U.S. Fish and Wildlife Service's California Condor Recovery Program.
The open-air tanks are used to store water for firefighters. During a wildfire, helicopter pilots drop lines from their aircraft into the tanks to suck up water that will be dropped onto the blaze.
The tanks were recently emptied as firefighting season wound down. Officials are looking into ways to keep the birds out of them before they are refilled next year.
The majestic birds nearly became extinct in the 1980s before wildlife officials captured the last remaining few and began an aggressive breeding program. As birds are successfully raised in captivity they are released into the wild. They have re-established a colony in the Tehachapi mountains, part of their historical habitat.
Their biggest threat has been lead poisoning from feeding on animals killed by hunters using lead bullets. One bird died of lead poisoning earlier this year and 21 others were treated for lead poisoning last month, according to the Los Angeles Zoo and Botanical Gardens.
Last month, California became the first state to ban hunters from using lead bullets, although the ban does not fully take effect until 2019.