“There’s something really confusing about the condor data.”

Those weren’t the words Oliver Ryder wanted to hear as he walked to his car after a long day’s work trying to save California condors, one of the most endangered animals on the planet. When his colleague Leona Chemnick explained what she was seeing, his dread quickly changed to fascination.

For decades, scientists have been trying to coax the California condor back from the edge of extinction. The entire population of these birds crashed to just 22 animals in 1982. By 2019, captive breeding and release efforts had slowly built the total population up over 500. Doing that has required careful management of captive birds, particularly selecting which