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Earth Notes: Condor Parthenogenesis

Joseph Brandt/USFWS

California condors don’t have an easy time raising their chicks. The eggs take two months to hatch, and it’s a full year before the baby birds can live on their own. But now scientists know condor mothers can skip a step in the baby-making process if they want to. They don’t have to mate with a male to lay a healthy egg.

Scientists with the San Diego Zoo Wildlife Alliance did extensive genetic testing on condors in captivity and unearthed a surprise. Two eggs had hatched into babies that didn’t have any genetic material from a father.

This form of asexual reproduction is called parthenogenesis. It’s common in nature in a wide range of species, from sharks to snakes to starfish. But it’s rare in birds and scientists thought it only occurred when the mother couldn’t find a suitable mate. That wasn’t the case here. Both the female condors had mated before and still had access to a male. It’s a mystery why they chose to skip mating and go straight to egg-laying. The resulting baby chicks are referred to as “parthenotes.”

As a species, California condors are imperiled by lead poisoning and other human-created threats. Only about three hundred condors live in the wild. With ten-foot wingspans, the birds look primeval as they soar over the Grand Canyon or the rock pinnacles of southern Utah. Their numbers are rebounding thanks to a captive breeding and release program. The parthenote chicks offer hope for a species that is endlessly innovative in its struggle to survive.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.