Author Jacqueline Detwiler Illustration James Provost
When he was 13, Ben Novak wanted to revive the extinct dodo—a very tricky feat, even today. But 13 years later, Novak has a pretty good shot at bringing back another extinct avian species: the passenger pigeon. He’s the lead researcher on a project launched by a foundation called Revive & Restore, which aims to repopulate the Earth with the peach-breasted birds that once populated the eastern seaboard so thickly that flocks blotted out the sun. Passenger pigeons went extinct almost exactly 100 years ago, so re-establishing their substantial flocks will be a challenge. Revive & Restore’s co-founder and executive director, Ryan Phelan, estimates that the project will take 10 years, assuming that all of the pieces fall into place. And that’s probably an optimistic estimate: Scientists will have to sequence the genomes of the passenger pigeon and its closest living relative, combine the two, insert the resulting DNA into stem cells in eggs, hatch chicks and breed the chicks’ offspring to pull it off. Here’s how they’ll do it.
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1. “All ancient DNA has holes in it,” says Phelan. To repair the holes, researchers will compare the DNA from a bunch of passenger pigeon museum specimens to that of their closest living relative, the band-tailed pigeon. They’ll figure out which genes code for passenger pigeon–specific traits, like that colorful breast, and add them in if they’re missing.
2. Next, researchers need to turn the DNA into birds. The scientists plan to insert the DNA into germ cells meant to become sperm or eggs, then stick those into the eggs of rock pigeons. The hatchlings will still be rock pigeons, but if all goes well, their sperm or eggs should be those of passenger pigeons. Breeding them with each other will produce the final birds.
3. To ensure survival, the new chicks will need to be raised like passenger pigeons by surrogates from other pigeon species. These surrogates will be trained in advance to eat a passenger pigeon diet and may be dyed to resemble adult passenger pigeons. There are even plans to use homing pigeons to train the fledgling passengers to migrate properly.