For two months this spring, two California condor parents carefully cared for a single, huge egg. They took turns sitting on the egg to keep it warm, and they turned it regularly, a behavior thought to promote healthy chick development.
What the birds, which were part of a breeding population at the Oregon Zoo, didn’t seem to notice was that the egg was a high-tech fraud. The plastic shell, made with a 3D printer, was stuffed with sensors designed to surreptitiously monitor conditions inside the condor nest.
For weeks, the dummy egg tracked nest temperature, recorded the birds’ egg-turning behaviors, and recorded ambient sound. The zoo hopes this data will allow it to better replicate natural conditions in the artificial incubators that are essential to its condor-rearing efforts.
California condors, which can have a wingspan 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 puts them safely in the incubators. This strategy has several advantages, encouraging some couples to lay a second egg, allowing the zoo to monitor the development of the embryos and protecting the fragile embryos from the ruckus of the condor.
“During the breeding season, tensions tend to rise,” said Kelli Walker, the zoo’s senior condor keeper. “And sometimes couples fight in the nest chamber and accidentally injure the egg.” (Chicks are returned to the nest when they begin to hatch.)
The more closely the zoo can replicate the natural conditions in the incubators, the more successful it will be. So Ms Walker enlisted Scott Shaffer, animal ecologist and bird researcher at San Jose State University, and Constance Woodman, bird scientist and conservation technology expert at Texas A&M University, who together created data logging smart eggs for many different birds. species.
This is how they created condor eggs:
Design the eggs
Dr. Woodman has created a digital model of the imitation condor egg. The hull needed to be thin enough for internal sensors to detect temperature changes, but tough enough to withstand possible avian abuse. (A macaw once threw one of Dr. Woodman’s eggs out of its nest, two stories above the ground.) To make sure the egg wouldn’t split open, she designed threaded shell halves that snap together. would screw tight. “It will stay closed unless you have thumbs up,” she said. “Birds don’t have thumbs, so we’re in good shape.”
Print the seashells
Dr. Woodman used a 3D printer loaded with a plastic specially selected to be safe for birds, which could spend months sitting on the eggs. “I really, really don’t want to do well and poison a bird,” she said. Printing each shell took 13 hours.
To make sure the egg wasn’t prone to spinning or wobbling, Dr. Woodman gave it to Loretta, her litter-trained “house turkey,” she said. “If Loretta doesn’t like it, she won’t sit on it.”
Dye the eggs
The color of bird eggs varies by species, and Dr. Woodman and Dr. Shaffer always try to replicate it as closely as possible. To match the subtle blue-green hue of condor eggs, Dr. Woodman dipped the shells in a jar of a non-toxic dye intended for children’s clothing.
Small data loggers hidden inside the shells can track egg temperature and movement. An audio recorder picks up sounds in the nest, which the zoo will play back to the eggs in the incubator. “Developing embryos can hear things through their shells,” Walker said. And she used electrical tape to cover the electronics lights, “otherwise it would have looked like a flashing Christmas egg.”
weigh them down
Some birds reject abnormally light eggs. So Mrs. Walker used a hot glue gun to fix rocks inside the egg, bringing its weight to over half a pound.
make the exchange
The first condor parents to receive a smart egg this year were a female known only as number 762 and her mate, Alishaw. “He’s not what you would call a traditionally fantastic dad,” Ms Walker said. “He’ll incubate as long as it takes, but he’s not thrilled about it.” (762’s devotion to him, however, remains intact. “She’s kind of a ride or die with Alishaw,” Ms. Walker said.)
When the two birds left the nest, zoo staff moved their real egg to an incubator and replaced it with the fake one. The condors didn’t seem to notice. (Their chick, which has since hatched, is back with her parents and doing well, Ms Walker said.)
Once the breeding season is over, Dr. Shaffer and Ms. Walker will analyze the data. The results will inform future incubator settings and, the team hopes, help bring more California condor chicks safely into the world. “It’s just a really cool use of technology that’s only going to get better,” Dr. Shaffer said.