A pair of California condors lost an egg but biologists secretly slipped a foster egg into the couple's mountain nest in a rappelling mission. Today, the condors are raising the newly hatched chick.

The female condor, #111, is 22 years old while the male condor, #509, is 7 years old. Their courtship started way back in 2014 and the two soon nested near the Hopper Mountain National Wildlife Refuge.

The union was successful, with #111 soon laying an egg. A team of biologists from the U.S. Fish and Wildlife Service (USFWS) set up a bird camera to monitor the fetus on March 2.

An egg test allowed the biologists to predict that the baby condor will be born between April 4 and 6. But then, the worst nightmare happened: the egg disappeared in the middle of the night sometime between March 20 and 21.

The bird cam was turned off at night to save power, so it didn't record what could have happened to the egg.

Folks from the Cornell Lab of Ornithology, the team who runs the bird cam, said a predator most likely snatched the egg, leaving behind some eggshell fragments.

It was a heartbreaking moment for the condor couple but more troublesome for the researchers. The International Union for Conservation of Nature (IUCN) said these birds (Gymnogyps californianus) are critically endangered. In 2010, the agency tallied a total of 104 adult condors living in the wild, in which only 44 were only able to produce offspring that survived.

After the original egg went missing, the biologists schemed to relieve the couple of their loss. They replaced the lost egg with a fake one that both condors incubated soon after.

This gave the team a window to look for a foster egg, and they received one from the Los Angeles Zoo. On April 3, the team rappelled again to replace the fake egg with the foster egg, which finally hatched on April 4. It was the first California condor whose live hatching was observed on a bird cam.

To date, the team doesn't know the sex of the 9-ounce chick. This information will be verified with a blood test set sometime during its first year.

The Cornell team expressed that they will continue monitoring the condor family. To capture nighttime images, the team placed a new motion-activated Bushnell game camera.

Photo: Rennett Stowe | Flickr

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