Moribund burial beetle getting a new lease on life

Once, the American burying beetle - known for the unusual subterranean habits that inspired its name - was found throughout the Northeast. But the beetles have largely vanished from the region, except for a population that lives on Block Island off Rhode Island.

Now, a 15-year effort to reintroduce the black-and-orange beetle is showing signs of success, right under tourists’ feet on Nantucket. At least 150 beetles - and probably many more - are surviving in the wild here each year.

The 1-inch beetle’s shot at survival marks a discernible shift in the protection of rare species. Rather than focusing primarily on animals at the top of the food chain, scientists increasingly are training their survival skills on the less cuddly creatures that form the building blocks of earth’s ecosystem.

“People need to care about more species than just polar bears,’’ said Lou Perrotti, the conservation programs coordinator at the Roger Williams Park Zoo in Rhode Island, who is helping spearhead the reintroduction. Perrotti is so dedicated to the beetle he has a tattoo of one on his forearm. “This is a beautiful bug.’’

The beetle used to be found in 35 states throughout the Midwest and East but has vanished from 90 percent of its range. Today, populations exist in Arkansas, Oklahoma, Kansas, Nebraska, South Dakota, Texas - and Block Island. The bug was listed as endangered by federal scientists in 1989.

It’s a mystery exactly why the beetles’ numbers plummeted, especially since other meat-eating beetle populations in the same places remain healthy.

But Perrotti and other researchers on Nantucket, where the beetle had vanished in 1926, hope that if they are successful at bringing the bug back, they might also discover what made it disappear.

One recent gray day, Perrotti and a team of interns from the Maria Mitchell Association’s Natural Science Museum loaded up the back of a vehicle with more than 80 beetles they had recently caught in the wild and a plastic bag filled with dead quail. Six miles away on conservation land, the team dug a foot-deep hole. They carved a chamber off it about the size of a fist, where they placed the bird.

Carefully, Perrotti lifted the lid of a quarter-pint deli container and took a beetle out.

“Come here, sweetie,’’ he said as he positioned the bug on the quail carcass. The beetle began scurrying over the carcass as the team filled in the hole. They staked a wire screen over it to prevent seagull and crow attacks and set out to dig 43 other holes across the island’s Eastern End.

A century ago, the beetles would have found the dead animal and buried it on their own.

The insects’ chemical sensors can detect a carcass 2 miles away within hours of an animal dying. After flying to it, a pair of beetles begin excavating - slowly sinking the carcass into the earth and leaving little sign on the surface that it was ever there.

As the carcass is lowered, the beetles trim off feathers or fur. Then they mold the animal until it looks like a mushy gray tennis ball, coating it with antibacterial bodily secretions. Inside, the meat stays pink and fresh.

Beetle eggs hatch nearby, and the larvae find their way into the carcass, where they devour everything but the bones over the next two weeks, each larva growing to the size of a pinky.

In late summer, the larvae will emerge as beetles and feed on other insects until the following year - when they begin looking for a dead animal for their own offspring “nest.’’

Scientists marvel at their life cycle, but it is the beetle’s personality that really wins them over.

Parents regurgitate food to feed larvae and continually tend the carcass, removing fungi and covering the mushy ball with secretions. Beetle larvae even beg for food by stroking the mandibles of the adult.

“You just don’t see that extended parental care in insects very often,’’ said Michael Amaral, an endangered species biologist with the US Fish and Wildlife Service who oversees the American burying beetle program.

In fact, Amaral says, the beetle’s decline was first noted by behavioral ecologists who were finding fewer and fewer in the wild to bring into labs to study.

Scientists suspect the beetle numbers may have plummeted because much of their living space was gobbled up by development. The beetles are also picky about their “nests,’’ choosing carcasses only about the size of a mourning dove. That’s because if the body is too small, there won’t be enough food for the beetle to raise more than a few young and if it’s too big, the beetles can’t bury it. But populations of ground-nesting birds have precipitously declined. And some birds that were of optimum size for the beetle to reproduce on, such as the passenger pigeon or heath hen, are extinct.

Nantucket was chosen for the beetle reintroduction because it is so similar to Block Island, with plenty of undisturbed lands thanks to the Nantucket Conservation Foundation and Mass Audubon. And it doesn’t have any skunks or raccoons that could compete for dead animals.

So 15 years ago, the US Fish and Wildlife’s Amaral and staff at the Roger Williams Zoo began releasing beetles at Audubon’s Sesachacha Heathlands Wildlife Sanctuary. They stopped in 2005 after releasing about 3,000.

Since then, Perrotti and his interns monitor the population by baiting scores of traps filled with rotted chicken, buried in the ground. Starting about 6 every morning in the early summer, they check the traps.

“Got one!’’ exclaimed Perrotti one recent morning as he plucked a beetle from a trap with forceps. The bug was then brought to the science museum to be weighed, examined, and given identifying marks before being paired with one of the opposite sex in a deli container. A few days later, they were placed on a quail in the ground.

The team has caught more than 110 beetles this year. Perrotti conservatively estimates there are 150 beetles on the island, but there are probably many more. Last week, one was found on the western end of the island, where a reintroduction effort was halted several years ago.

“That means they persisted there and are finding food on their own,’’ he said.

It’s not clear the Nantucket beetles can survive long-term on rabbits or other small animals there if the research team stops giving them quail.

There are bigger questions. Unlike larger animals that can serve as ambassadors to protect lands that support hundreds of additional species, the American burying beetle is probably protecting only one other species, some tiny white mites that live on it. And the bug’s reputation as a critical recycler in nature is fading.

“By the time [most species] are rare, they have lost their ecological importance,’’ said David Wagner, professor of ecology and evolutionary biology at the University of Connecticut.

Wagner still says they should be saved. Their impressive chemical arsenal may one day be useful in pharmacology or biotechnology. And since humans probably played a role in their decline, there is a moral argument that people should try to bring them back.

Perrotti agrees and notes the bug’s reintroduction costs only about $3,000 a year.

As he gazed at a placid burying beetle in a deli container in the rain last week, he gave it a loving smile. “It certainly has personality.’’

Beth Daley can be reached at bdaley@globe.com.