LOS ANGELES (CBSLA.com) — A record 21 California condors were brought in to the Los Angeles Zoo this month to be treated for lead toxicity, zoo officials said Tuesday.

Condors brought in to the zoo’s Gottlieb Animal Health and Conservation Center typically appear healthy, but tests show high levels of lead, prompting treatment, said Dr. Curtis Eng, the chief veterinarian of the zoo’s California Condor program. But lately, these endangered birds have been coming in visibly sick.

READ MORE: Enrollment Down 6% At LAUSD Schools

“These birds have been coming in at a low body weight, not eating at all, and showing signs of crop stasis, when the stomach stops moving food,” Eng said. “That’s scary to see so many clinically sick birds.”

READ MORE: 'Banksy: Genius Or Vandal' Exhibit To Open In Early October

Gov. Jerry Brown signed legislation on Oct. 11 that requires hunters in California to use non-lead ammunition. The law will phased in by 2019.

MORE NEWS: Latino Restaurant Association Kicks Off DINE LATINO Restaurant Week

“Reducing and eventually eliminating the use of lead ammunition is an essential step in condor recovery,” said John McCamma, California condor recovery coordinator for the U.S. Fish and Wildlife Service.