Image Source: https://www.audubon.org/
On June 1, a tiny Florida Grasshopper Sparrow scurried out of an outdoor aviary and onto conservation lands south of Orlando, joining a fragile but recovering population of the most endangered birds on the continent. Unbeknownst to the little brown bird, it was the 501st captive-bred Florida Grasshopper Sparrow to be released as part of a concerted breeding effort.
By 2017, the total population of the imperiled Florida Grasshopper Sparrow had fallen below 100, prompting federal, local, and private organizations to initiate a conservation breeding program that has since found surprising success. Today, about 15 captive breeding pairs lay eggs and raise young in carefully maintained outdoor enclosures at various locations. In 2019, the first batch of captive-bred offspring were released to help rebuild the wild population, which as of 2021 had rebounded to roughly 125 birds from a low of fewer than 30 breeding pairs in 2018.
“It’s exceeded all of our wildest expectations,” Julie Wraithmell, executive director of Audubon Florida, says of the program. “They’ve bred well in captivity, and they’ve survived on the prairie and gone on to breed on the prairie.”
Key to the program’s early success has been the close collaboration among a variety of organizations, including the U.S. Fish and Wildlife Service (FWS), the Florida Fish and Wildlife Commission (FWC), Fish and Wildlife Foundation of Florida, White Oak Conservation, the Avian Preservation and Education Conservancy, and Audubon Florida. By sharing breeding strategies, triumphs, and failures, the group has been able to halt the sparrow’s slide toward extinction.
Despite this monumental achievement, however, all of the partners are careful to note that these measures should be considered a last resort. “This conservation breeding program buys us time to continue to do research, to try to understand what are the causes of the decline,” says Juan Oteyza, an FWC biologist who helped spearhead the effort.
As comfortable on the ground as it is in the air, the Florida Grasshopper Sparrow is an orange-cheeked bird with the habits of a mouse and the buzzy voice of a bug. A subspecies of the more widespread Grasshopper Sparrow, the secretive birds live solely in central Florida’s grasslands. In the 1990s and 2000s, after decades of gradual decline due to habitat loss—more than 90 percent of Florida dry prairie has been destroyed—Florida Grasshopper Sparrow populations mysteriously began to collapse.
With numbers cratering, desperate conservationists scrambled to create a captive breeding program to help save the birds. The 1987 extinction of Florida’s Dusky Seaside Sparrow was still fresh in their minds: By the time breeding programs were attempted for that subspecies, it was too late—there weren’t enough birds left.
No one wanted to repeat the same mistake with the Florida Grasshopper Sparrow. “That has always been in the back of our minds: Don’t wait too long,” says Mary Peterson, an endangered species recovery biologist with FWS. But that didn’t make the decision to capture some of the few remaining sparrows any easier.
Fortunately, the sparrows adapted well to captivity—much better than anyone had expected.
“Nobody wants to see a wild bird put in a cage,” Peterson says. “We just knew that if we didn’t do something that the population was headed to extinction.”
Fortunately, the sparrows adapted well to captivity—much better than anyone had expected. Protected and with plenty of food, the birds thrived, with some producing multiple broods in a season. Concerns over how the captive-bred chicks would adapt to wild habitat upon release were also quickly quelled; their genetic hardwiring kicked in, and they were able to forage, sing, and breed without issue.
“We were not sure if they were going to be able to even survive,” says Adrienne Fitzwilliam, avian conservation coordinator at FWC. “They not only survived, but they also started breeding, and this helped grow the overall numbers of birds in the wild population.”
According to Oteyza, roughly 30 percent of the captive-bred birds have been found to remain at the release site. And up to 20 percent are breeding—impressive numbers for any songbird breeding program, he says.
Oteyza credits the coalition’s strategy of balancing habitat management, nest protection, field research, and outreach to private landowners for much of the program’s success. “What we have used for Florida Grasshopper Sparrow is this multi-pronged approach—not just putting all our eggs in one basket, if you will,” he says.
With the population stabilized and heading in the right direction, determining the root cause of the Florida Grasshopper Sparrow’s decline is a priority for the program. Researchers have studied factors like predation, flooding, fire, genetics, and land management, but the exact cause remains unclear. Still, the partners have made discoveries that will further aid the program and also inform efforts to save other endangered birds.
Though many questions and challenges remain, the program’s success has given conservationists cause for cautious optimism. “The first time you capture a wild bird and put it into captivity is heart-wrenching,” Peterson says. “But then when you see these birds returning to the prairie, it makes it worth it.”