On March 7, a tiny beak began tapping through an eggshell at the San Diego Zoo Safari Park. Ten days later, a second Socorro dove hatched. A third followed in late April. To most people, these birds look unremarkable — close cousins of the mourning doves that perch on backyard fences across North America. But Socorro doves are anything but ordinary. Only around 200 exist on Earth, every single one in captivity. The last wild individual was recorded in 1972, on a remote volcanic island off Mexico’s Pacific coast — and the species has not been seen there since.
A species kept alive by zoos alone
Every Socorro dove alive today lives behind wire. Roughly 200 birds are distributed across approximately 50 institutions on three continents — a fragile network assembled over decades to prevent a permanent disappearance. The breeding effort is coordinated under the Socorro Dove Project, with a stated goal of returning birds to Socorro Island by 2030.
In 2025, eight Socorro doves hatched at Chester Zoo in England. Whipsnade Zoo recorded its own hatchling, Bird Paradise in Singapore welcomed two chicks — the first of the species ever born at that facility — and San Diego added three more. Each birth adds a small but meaningful margin against total loss.
“These recent hatches represent a significant source of hope and progress for Socorro dove conservation efforts,” says Jenna Stallard, wildlife care manager for birds at San Diego Zoo Safari Park. “Each successful hatch is an important step toward securing the future of this species.”
How sheep and cats erased a species from its homeland
Socorro Island sits roughly 370 miles off Mexico’s Pacific coast — remote, volcanic, and once rich with endemic life. More than 150 years ago, humans introduced 100 sheep to the island. By 1960, that population had grown to 5,000, and the feral animals had overgrazed the vegetation while destroying the low-lying nest sites the doves depended on.
The trouble compounded in the 1950s when Mexico established a naval base on the island and residents brought cats. “When the sheep destroyed that area, they were damaging the Socorro dove so bad that when cats arrived, the doves were already in deep trouble,” says Juan Esteban Martínez Gómez, a scientist with Mexico’s Institute of Ecology leading restoration efforts on the island. Habitat destruction, he emphasizes, was the primary driver.
The Socorro dove prefers walking to flying — a trait that, according to the Cornell Lab of Ornithology, may have accelerated its decline once feline predators arrived.
Rebuilding a forest before the birds can return
Between 2009 and 2012, a coordinated eradication effort removed all feral sheep from Socorro. A 2016 study confirmed measurable recovery in vegetation cover and improvement in soil quality. Since 2015, Martínez and his teams have been planting native trees on the island, researching germination techniques to speed along species that mature slowly.
The doves themselves are built into the restoration plan. “The Socorro dove is a very important seed disperser,” Martínez says. “It’s a bird that pretty much eats all the fruits of these endemic trees of Socorro Island.” Once reintroduced, the birds could help the forest regenerate on its own — a feedback loop the island has not had in decades. The restoration also stands to benefit the Socorro mockingbird and the Socorro Island tree lizard, both endangered.
What 37 bird generations in captivity taught scientists
Socorro doves have now lived under human care for approximately 37 bird generations. Zoos have documented breeding behaviors, pair bonding patterns, and nest-site preferences — information that will directly shape reintroduction planning. A practical constraint has also emerged: reproductive potential drops off after about five or six years of age, meaning any birds selected for release will need to be young enough to establish a viable breeding population in the wild.
One finding offers particular encouragement. Captive doves have retained their natural wariness of aerial predators, including the endemic Socorro red-tailed hawk. At Africam Safari, a zoo outside Puebla, Mexico, captive Socorro doves have access to aviaries planted with trees native to Socorro Island — giving them early familiarity with the vegetation of their ancestral home.
The final steps toward freedom
In collaboration with the Mexican Navy, conservationists have built an aviary on Socorro Island to receive incoming birds. New arrivals will be quarantined, then moved to a release pen before entering the wild. Martínez is direct about the timeline: “Within one or two years, this is probably going to happen.” Feral cats still roam parts of the island, though, and a small founding population could be lost quickly without active predator management.
Conservationists describe this project as more than a single-species rescue. “It is more vital than ever that we protect these rare birds,” says John Ewen, a professor in species recovery at the Zoological Society of London’s Institute of Zoology. The next few years will test whether decades of careful preparation translate into something that has not existed since 1972: a Socorro dove walking freely across its native island.