Officials with The Peregrine Fund announced Wednesday that tests show a significant drop in the percentage of condors in Arizona and Utah that have toxic levels of lead.
Biologists with the Idaho-based nonprofit say data from September shows 16 percent of the endangered birds trapped and tested had dangerous blood-lead levels, down from 42 percent the previous season.
Wildlife officials say 11 birds have been treated with lead-reducing therapy, compared to 28 last year.
Officials say last year was the second-worst on record for condor deaths and lead exposure since their 1996 reintroduction in Arizona.
Researchers say the decrease may be due to more hunters using non-lead ammunition.