ST. LOUIS — For seven years, the St. Louis Zoo bred, raised and released hundreds of endangered American burying beetles on one Missouri prairie.
This spring, after a two-year break, the zoo discovered that the beetles are still breeding there and seem to have created a self-sustaining population.
It’s a key moment in scientists’ efforts to restore the species in the state.
“Ultimately, that’s what we’ve been working towards all these years,” said Kayla Garcia, the zoo’s manager of invertebrates.
Dozens of species large and small go extinct every day worldwide. But scientists say preserving small creatures like the American burying beetle is important: Some play a key role in their environments, linked to the survival of dozens of other species. And some of those may be impacted by the same threats. Moreover, animals like the burying beetle can also serve as figureheads to help people care about the broader ecosystems.
“For every story that we know, there are vast, vast fields of things that are imperiled, that we don’t even know are imperiled,” said Steven Buback, a natural history biologist with the Missouri Department of Conservation. “This is a good poster child for invertebrate conservation.”
Once found throughout 35 states, wild American burying beetles are now found in only seven states, according to the U.S. Fish & Wildlife Service.
“People aren’t quite sure why they declined,” Garcia said.
The beetle was listed as endangered under the Endangered Species Act in 1989. At the time, the species had not been seen in Missouri since 1980, according to the zoo.
Buback said two rounds of statewide surveys were conducted in the 1990s.
“They came up empty,” he said.
Experts figure that pesticide use, habitat loss, light pollution and a lack of small animal carcasses all played a role in the beetle’s decline. One hypothesis is that the extinction of the passenger pigeon, once found in enormous flocks, meant less food for the beetle.
The zoo has been working with the Missouri Department of Conservation for 16 years to save the beetle.
The unseen work happens year-round, with dead quails and an insect matchmaking program, in a small laboratory inside the zoo, behind a black, windowless door.
The zoo breeds the beetles — first collected from Arkansas, the closest wild population — twice a year. A computer program tracks how the beetles are related and suggests pairings to prevent inbreeding. Beetles are not matched if they are more closely related than second cousins.
Then the zoo places the pairs in buckets with soil and the dead quail. The beetles bury the carcass and dig an adjacent chamber where the female lays her eggs. They strip the feathers from the bird and spread it with antimicrobial secretions from special oral and anal glands to keep it fresh.
“They turn the quail into more or less a preserved meatball,” Garcia said.
After the eggs hatch, the parents bring meat from the quail to feed their larvae as they grow.
American burying beetle broods are small, the parents provide an unusual level of care and attention. Both the male and female feed their larvae, clean them and even communicate back and forth by squeaking.
Zoo scientists, in cooperation with the department of conservation, the Nature Conservancy and the U.S. Fish & Wildlife Service, first released zoo-reared beetles in 2012 on western Missouri’s Wah’Kon-Tah Prairie, a site with a large quail population near wild beetles in Arkansas and Oklahoma.
They packed beetles in individual plastic containers, surrounded them with ice packs to keep them cool and drove them four hours across the state.
“My absolute favorite part of the whole process is being able to take those beetles out of their containers and physically put them back into the wild,” Garcia said. “There’s a lot of promise in the act of doing that.”
For seven years, researchers and volunteers released beetles at Wah’Kon-Tah — about 2,800 in total. And every year, they found overwintering beetles, an encouraging sign.
But in 2019, to see if the beetles could survive without assistance, the zoo stopped introductions at Wah’Kon-Tah.
“We liken it to taking the training wheels off this particular population,” Garcia said.
And last year, because of the COVID-19 pandemic, staff couldn’t survey the site at all.
This year, the big question was: Did the beetles survive on their own in the wild for three years?
In the last week of May, researchers returned to the prairie. They found nine beetles, a cause for celebration.
The team has recently shifted reintroduction efforts to the nearby Taberville Prairie Conservation Area, hoping to create a “metapopulation” of connected groups. Recent surveys have already found beetles that traveled a few miles from the release site.
In September 2020, the beetle was federally downlisted to “threatened,” following a lawsuit from Independent Petroleum Association of America several years before. In its ruling, the Fish & Wildlife Service denied the decision was due to lobbying from the oil and gas industry, saying instead that it was scientifically based. In March, the Center for Biological Diversity filed a lawsuit to restore endangered species protections to the beetle.
The beetle retains its endangered status on Missouri’s state list.
But Garcia said there is urgency to continue introducing the beetle in new locations, especially as climate change threatens its current range.
“Eventually, the goal is that we won’t have to do these introductions anymore,” said Garcia, “that they’ll be able to completely live their lives without any of our help, for generations out on the prairie.”
Editor’s note: An earlier version of this story incorrectly identified the burying beetle as the first insect listed as endangered under the Endangered Species Act.