He's been called the toughest four ounces on the planet.
He's just a bird, true, but he flies about 20,000 miles a year, bucking headwinds, and dodging storms - a death-defying trip he has been making for at least 21 years.
Each time researchers spot him, identifiable by the number B95 on an orange leg band, they figure it might be their last sighting.
No bird lives forever, they tell themselves.
But Sunday on Delaware Bay, shorebird scientists spotted yet again what has to be the world's most famous shorebird: a red knot in whose honor statues have been erected and a book written.
At 8 a.m., Argentinian researcher Patricia Gonzalez went out on the deck of the house that an international shorebird team rented at Reeds Beach, Cape May County. She trained her high-magnification scope on a small flock of red knots.
Suddenly, there he was.
She doubted it at first. An older black band was missing. The B95 on the orange band had faded.
She looked again. This time, she was sure.
"It's incredible . . . a miracle," Gonzalez said.
So the bird believed to be the longest-living of his species - although scientists do not know the typical life span - is still on the wing, still stopping off at the bay to refuel on horseshoe crab eggs before setting out on the final leg of a journey to the red knots' Arctic breeding grounds.
By now, he has traveled from the tip of South America to the top of Canada so many times he has been dubbed Moonbird, having flown the equivalent distance between Earth and the moon and more than halfway back.
Phillip Hoose, a Nature Conservancy staffer in Maine who followed the researchers for a year and wrote the 2012 book Moonbird: A Year on the Wind With the Great Survivor B95, was near the scene of the sighting Sunday. He raced over, hoping to get his first glimpse of the bird, but arrived minutes after a small plane few overhead and scattered the flock.
"Jilted again," Hoose later said. But it didn't lessen his admiration for Moonbird, which he said must be "nearly bionic," given his age and stamina.
The news reverberated among shorebird researchers throughout the hemisphere and beyond, and congratulations began pouring in.
By now, B95 has become a poster bird for his species - and their plight.
Every spring, they arrive on Delaware Bay shores, famished, their body reserves depleted. At exactly the same time, horseshoe crabs are coming ashore to lay their pearly green, lipid-rich eggs. The red knots spend about two weeks feasting, then head north.
But more than a decade ago, the birds' numbers began to drop drastically. The population on Delaware Bay went from about 100,000 to about 12,000 in 2003. Most shorebirds are in decline, but among those that come to Delaware Bay, red knots are the most imperiled.
Biologists blamed an overharvest of crabs, which are inedible for people but used as bait for the Asian delicacies, conch and eel.
In 1995, researchers began banding red knots to find out more about them. Gonzalez was on the team that banded B95 that year, in Argentina. He was an adult, at least two years old, and already a seasoned traveler.
At first, researchers did not look specifically for him. Typically, they scan flocks in search of all banded birds. Resightings give clues to their ages, the longevity of males vs. females, where the birds go, and how site-faithful they are. Do they visit many places, so if one locale is lost, they will turn to others? (In this case, Delaware Bay is crucial.)
As time passed, they kept seeing B95.
"None of us ever believed that B95 would live to be 21 years old and just keep going as strong as ever. But here we are. And now I think none of us would dare bet - 25, 30? Who knows?" said Charles Duncan, a Maine conservationist who has worked across the Americas and has been coming to Delaware Bay for five years.
Meanwhile, it's shaping up to be a good spring for the birds, said Larry Niles, a New Jersey researcher who has studied - and championed - the red knot for two decades.
The crabs have been spawning continuously on beaches scoured by Hurricane Sandy, but restored just in time. The birds - measured after being netted by the scientists - have been gaining weight. Many are ready to lift off and head north.
A preliminary count indicates their numbers may have rebounded to at least 26,000.
"I think it's going to be one of the best years we've had in 10 years," Niles said.
As for B95, Moonbird is "emblematic of the whole species hanging in there."