If there’s new hope, it’s blurry. What’s certain: the roller coaster tale of the ivory-billed woodpecker, a majestic bird whose presumed extinction has been punctuated by a series of contested rediscoveries, is going strong.

The latest twist is a peer-reviewed study Thursday in the journal Ecology and Evolution presenting sighting reports, audio recordings, trail camera images and drone video. Collected over the last decade in a Louisiana swamp forest, the precise location omitted for the birds’ protection, the authors write that the evidence suggests the “intermittent but repeated presence” of birds that look and behave like ivory-billed woodpeckers.

But are they?

“It’s this cumulative evidence from our multiyear search that leaves us very confident that this iconic species exists, and it persists in Louisiana and probably other places as well,” said Steven C. Latta, one of the study’s authors and director of conservation and field research at the National Aviary, a nonprofit bird zoo in Pittsburgh that helps lead a program that searches for the species.

But Dr. Latta acknowledges that no single piece of evidence is definitive, and the study is carefully tempered with words like “putative” and “possible.”

Therein lies the problem. As one expert wrote during a previous ivory bill go-round: “The body of evidence is only as strong as the single strongest piece — ten cups of weak coffee do not make a pot of strong coffee.”

This time, two experts who have been skeptical of previous sightings said they remained unconvinced.

“The trouble is, it’s all very poor video,” said Chris Elphick, a professor of conservation biology at the University of Connecticut who studies birds. Pileated and red-headed woodpeckers, among other species, can look a lot like ivory bills from a distance or from certain angles. Light can play games with the eye. Audio is easy to misconstrue.

“I don’t think this changes very much, frankly,” he said. “I would love to be wrong.”

A spokeswoman, Christine Schuldheisz, said the agency did not comment on outside studies but was working toward a final decision, which is expected later this year.

According to the authors of the new study, removing federal protection would be bad for any remaining ivory bills. But other scientists say there’s a steep price to keeping them on the endangered species list.

“Whether or not limited federal conservation funds should be spent on chasing this ghost, instead of saving other genuinely endangered species and habitats, is a vital issue,” said Richard O. Prum, a professor of ornithology at Yale.

Ivory bills fell into steep decline as Americans logged their habitat, old-growth swampy forests of the Southeast. Few remained by the 1930s, but a scientific expedition discovered a nest in Louisiana, in one of the largest remaining swaths of habitat. The land, called the Singer Tract, was leased for logging. Conservation groups tried to purchase the rights, but the company refused to sell. The last widely accepted ivory bill sighting in the United States was in 1944, a lone female, seen in her roost with the forest cleared around her.

Since then, purported sightings have sparked joy and backlash. One, in 1967, was heralded on the front page of The New York Times. Twenty years later, another one, in Cuba, where a subspecies or similar species may or may not hang on, was also reported on Page One. In 2002, searchers in Louisiana thought they’d captured audio of the ivory bill’s distinctive double rap, but a computer analysis determined the sound to be distant gunshots. A reported sighting in Arkansas in 2004 led to a paper in Science and flurry of bird tourism, but that evidence was heavily criticized.

To Dr. Elphick, a birder as well as a scientist, one of the most telling results is what so much effort has not yielded: a single clear photograph.

“There are these incredibly rare birds that live in the middle of the Amazon that people can get good, identifiable photographs of,” Dr. Elphick said. “And yet people have spent hundreds of thousands of hours trying to find and photograph ivory-billed woodpeckers in the United States. If there’s really a population out there, it’s inconceivable to me that no one could get a good picture.”

But Dr. Latta, the study co-author, insisted that he had seen one clearly with his own eyes. He was in the field in 2019 to set up recording units, and he figures he spooked the bird. As it flew up and away, he got a close, unimpeded view of its signature markings.

“I couldn’t sleep for, like, three days,” Dr. Latta said. “It was because I had this opportunity and I felt this responsibility to establish for the rest of the world, or at least the conservation world, that this bird actually does exist.”