For two months this spring, California condor parents carefully tended a single large egg. They take turns sitting and turning the egg regularly to keep it warm, a behavior believed to promote proper chick development.
What the birds, part of a breeding population at an Oregon zoo, don’t realize is that the egg is a high-tech hoax. The plastic shell, made with a 3-D printer, is filled with sensors designed to surreptitiously monitor conditions inside the condors’ nest.
For weeks, the dummy egg monitored the nest’s temperature, logged the birds’ egg-turning behavior and recorded ambient noise. The zoo hopes this information will allow it to better replicate natural conditions in artificial incubators, which are key to its condor breeding efforts.
California condors, with wingspans of nearly 10 feet, are critically endangered. So every year when the birds lay their eggs, the zoo takes them out of the nest and into the safety of the incubators. This strategy has several advantages, prompting some pairs to lay a second egg, allowing zoos to monitor embryo development and protect fragile embryos from condor predation.
“During breeding season, tensions run high,” said Kelly Walker, the zoo’s condor keeper. “And occasionally a couple will fight in the nest room and accidentally damage the egg.” (The chicks return to the nest when they hatch.)
The more closely the zoo can reproduce the natural conditions in the eggs, the more successful it will be. So Ms. Walker teamed up with Scott Shafer, an animal ecologist and ornithologist at San Jose State University, and Constance Woodman, a bird scientist and conservation technology expert at Texas A&M University, to create smart eggs that can enter data for many different birds. Species.
Here’s how they brought the condor eggs:
Design the eggs
Dr. Woodman created a digital model of a simulated condor egg. The shell had to be thin enough for internal sensors to detect temperature changes, but thin enough to withstand a potential avian attack. (A macaw once dropped one of Dr. Woodman’s eggs from her nest, two stories above the ground.) To keep the egg from breaking open, she held the shell halves firmly in place. “Until you find the thumb, it stays closed,” she said. “Birds don’t have thumbs, so we’re in good shape.”
Print the shells
Dr. Woodman used a 3-D printer loaded with plastic specially selected for the safety of birds, which can take months to sit on the eggs. “I really don’t want to say good and I don’t want to poison a bird,” she said. It took 13 hours to print each shell.
Dr. Woodman gave the egg to Loretta, a litter box-trained “house turkey” to make sure the egg was prone to rolling or swinging. “Loretta, if you don’t like it, you don’t sit on it.”
Color the eggs
The color of bird eggs varies by species, and Dr. Woodman and Dr. Shafer always try to replicate it as closely as possible. Dr. Woodman dipped the shells in a pot of non-toxic dye intended for baby clothes to match the subtle, blue-green color of the condor’s eggs.
Small data logs embedded in the eggs can monitor the eggs’ temperature and movement. A voice recorder records the sounds in the nest, which the zoo plays back in the eggs in the enclosure. “Developing embryos can hear things in their shells,” Ms Walker said. And she used electrical tape to cover the electronic lights, “otherwise it would look like a sparkly Christmas egg.”
Some birds reject eggs with unusual lighting. So Mrs. Walker used a hot glue gun to attach rocks to the inside of the egg, making it weigh more than half a pound.
Do the swap
This year, the first parents to receive a Smart Egg were a woman identified as number 762 and her partner Alishaw. “He’s not what you would traditionally call a wonderful father,” Ms Walker said. “He thrives as long as he’s there, but he’s not happy about it” (762’s commitment to him, however, remains undiminished. “She’s a ride-or-die type with Alisha,” says Mrs. Walker.)
When both birds left the nest, zookeepers took the real egg into the incubator and replaced it with the fake one. The condors didn’t seem to notice. (The chick has since been reunited with its parents and is doing well, Ms Walker said.)
Analyze the data
When the breeding season is over, Dr. Shaffer and Mrs. Walker will analyze the data. The findings will inform future incubator settings and, the team hopes, help bring more California condor chicks safely into the world. “The best use of technology will only make it better,” Dr. Shaffer said.