The California condor is the largest bird in North America. It has a wingspan of almost 10 feet (3 meters)! These scavengers have sharp eyesight that helps them spot dead animals from the air. They use their hooked beaks to rip apart the animals’ flesh. “Condors can clean up carcasses superfast,” says Kelli Walker, a condor keeper at the Oregon Zoo.

California condors once soared across western North America, from Mexico to Canada. That began to change in the mid-1800s when settlers arrived. To try to rid the land of predators, the settlers poisoned wolves and bears.

Condors ate the poison and died too. Because of poisoning and other threats, condors’ numbers plummeted. By 1982, only 22 wild condors were left.

To save them, people caught the last birds and moved them to breeding centers. There, scientists are working hard to bring their population back. The birds still face risks in the wild. But thanks to scientists’ efforts, condors’ numbers are almost up to 600 today (see Condors on the Rise, below).

The California condor is the largest bird in North America. It has a wingspan of almost 10 feet (3 meters)! These scavengers have sharp eyesight to spot dead animals from the air. They have hooked beaks to rip apart the animals’ flesh. “Condors can clean up carcasses superfast,” says Kelli Walker. She’s a condor keeper at the Oregon Zoo.

California condors once soared across western North America, from Mexico to Canada. That began to change in the mid-1800s when settlers arrived. They wanted to rid the land of predators. So they poisoned wolves and bears. Condors ate the poison and died too. This and other threats caused condors’ numbers to drop. Only 22 wild condors were left by 1982.

People caught the last condors to save them. They were moved to breeding centers. There, scientists worked hard to increase their numbers. The birds still face risks in the wild. But scientists’ efforts have helped. Nearly 600 condors exist today (see Condors on the Rise, below).

Each winter at the Oregon Zoo’s condor breeding center, zookeepers wait for each female condor to produce one precious egg. In the wild, eggs can break by accident. That’s why at the Oregon Zoo, workers place condor eggs in incubators. These machines keep the eggs safe and warm.

With the real condor eggs safe in an incubator, Walker places fake eggs in the condor nests. This tricks the parents into thinking they are caring for real eggs and helps prepare them to care for the hatchlings when they are born. After nearly two months, just before the real eggs hatch, workers return them to their parents to raise.

Once the birds have grown, zookeepers train them to survive in the wild. At a year-and-a-half old, they’re ready! Since 2003, the Oregon Zoo has released more than 70 birds.

Every so often, despite the scientists’ efforts, an egg doesn’t survive. In the wild, condor chicks listen to their parents’ breathing and heartbeats through the eggshells. Walker wondered if scientists could record these sounds and play them for the eggs in the incubator. Would that help the eggs develop—and the condor chicks survive?

A female condor lays one precious egg each winter. Zookeepers at the Oregon Zoo’s condor breeding center wait for this to happen. Eggs can break by accident in the wild. That’s why workers place condor eggs in incubators at the zoo. These machines keep the eggs safe and warm.

Walker then puts fake eggs in the condor nests. This tricks the parents into thinking they’re caring for real eggs. It also prepares them to care for their actual babies when they’re born. The real eggs are ready to hatch after about two months. Workers return them to their parents to raise the chicks.

Zookeepers train the birds once they’re grown. They learn to survive in the wild. They’re ready when they’re a year-and-a-half old! The Oregon Zoo has released more than 70 birds since 2003.

Every so often, an egg doesn’t survive. That’s even with scientists’ best efforts. Wild condor chicks listen through their eggshells. They can hear their parents’ breathing and heartbeats. Walker wondered if scientists could record these sounds. Then they could play them for the eggs in the incubator. That might help them develop. Then more condor chicks would survive.

Luckily, a tool already existed that could help Walker answer her question: a fake bird egg that contained technology to sense motion and temperature. Scientists had used the device in the nests of birds like parrots and arctic ducks. Walker contacted the scientists. Could they create a condor egg decoy that could record sounds in the condor nest? The scientists said yes!

Constance Woodman, a researcher at Texas A&M University, built the “smart eggs” with a 3-D printer. She used thin, sturdy plastic and dyed it pale green. “It looked just like a condor egg,” says Walker. To make sure the smart egg had the same weight as a real egg, Walker glued stones inside it.

But would condors accept the fake? In the spring of 2022, it was time to find out. The first pair to sit on a smart egg were a female known as number 762 and her male partner. The birds treated the egg like it was their own!

But soon, Walker’s team ran into a snag. The smart egg recorded the parents’ breathing. But it didn’t pick up the sounds of the parents’ heartbeats. Next, Walker plans to try a different microphone inside the egg. “Once we get the heartbeats, we’ll play them for the real eggs,” says Walker.

Those sounds will help make incubators feel more like real condor nests to developing chicks. Scientists hope that will help them meet their goal: to make sure every bird in their care survives. “Each egg is important,” says Walker.      

Luckily, a tool already existed. It was a fake bird egg. It had technology to sense motion and temperature. Scientists had used the device already. They’d placed it in the nests of birds like parrots and arctic ducks. Walker spoke to the scientists. She asked if they could create a condor egg decoy. It would need to record sounds in a condor’s nest. The scientists said yes!

Constance Woodman is a scientist at Texas A&M University. She built the “smart eggs ” with a 3-D printer. She used thin, sturdy plastic. She dyed it pale green. “It looked just like a condor egg,” says Walker. Walker glued stones inside the smart egg. That gave it the same weight as a real egg.

Would condors accept the fake? It was time to find out in the spring of 2022. The first pair of condors sat on a smart egg. They were a female known as number 762 and her male partner. The birds treated the egg like it was their own!

But Walker’s team soon ran into a snag. The smart egg recorded the parents’ breathing. But it didn’t pick up the sounds of their heartbeats. Next, Walker plans to try a different microphone inside the egg. “Once we get the heartbeats, we’ll play them for the real eggs,” says Walker.

Those sounds will help chicks in incubators. They’ll feel more like they’re in actual nests. Scientists hope that will help meet their goal. They want to make sure every bird in their care survives. “Each egg is important,” says Walker.