Toughest 4 ounces on planet?

Moonbird
A Year on the Wind with the Great Survivor B95
By Phillip Hoose
Farrar Straus Giroux.
160 pp. $21.99

It was Feb. 20, 1995. The bird-banding team had caught so many birds that they ran out of the usual colored bands.

Someone found black plastic in one of the trucks, and they fitted strips of it around the legs of the final birds, including one very special bird - a small shorebird that probably has become one of the most iconic birds known.

Although he was later fitted with an additional orange band bearing the inscription B95, it is the black band that served as the initial tipoff when, as the years passed, scientists spotted him again and again - far more often than they dared hope, far longer than anyone knew his kind could live.

B95 is a remarkable member of a remarkable subspecies - the rufa red knot. These birds have one of the longest migrations on the planet, every spring making their way from the southern tip of South America to their nesting grounds in the high Arctic, a journey of nearly 10,000 miles.

By now, B95 has been flying this route for about two decades. Scientists tallied his total distance - the equivalent of all the way to the moon and halfway back.

So they nicknamed him the Moonbird.

Newbery nominee and National Book Award-winning author Phillip Hoose was looking for a new book project when he heard about B95, and he was hooked.

This bird, he figured, could well be the toughest four ounces on the planet.

He set out to follow the birds, telling their story through the lens of Moonbird, and vice versa. It's an elegant interplay of birds, biologists, and B95 in Moonbird.

Ostensibly, the book is for young readers. But why limit such fine writing, engaging science, and remarkable occurrences to kids? Adults will find plenty here to stimulate their brains and send their imaginations soaring into the beyond with these extraordinary birds.

You want science? How about Herbst corpuscles? They are nerve receptors on the tip of a red knot's bill that detect the presence of nearby food when the bird jabs its bill into the sand. The book is sprinkled with such tidbits.

You want a wealth of detail? As red knots prepare for their long migration, organs they don't need for flight shrink to make more room for body fat.

What originally sparked scientists' interest in the rufa red knot was that it began a precipitous decline in numbers. When B95 was first banded, his peers totaled about 150,000. Now, the flock is down to about 25,000.

Researchers such as New Jersey's Larry Niles began to suspect it was because the birds weren't getting enough fuel on their most important stopover - Delaware Bay.

In a dance that had been going on for eons, horseshoe crabs would come ashore to spawn just as the birds arrived, and the lipid-rich eggs gave these fliers enough energy to finish the journey. But the crab harvest had increased, and the eggs had declined.

Scientists began catching the birds so they could weigh them, get blood samples, and glean other important data.

By now, the red knot may well be the most-studied shorebird on Earth.

Teams of watchers with spotting scopes have staked out the beaches - logging the band numbers of birds to add to population data.

Frequently, B95 was among them. From 2005 to 2009, he was spotted 23 times on Delaware Bay alone. He began to achieve bird celebrity.

The tale has many pivotal moments. Before 1979, scientists didn't even know where the birds went in spring. Then, Brian Harrington of the Manomet Center for Conservation Sciences sent a letter to shorebird enthusiasts, asking if anyone knew where there were more than 20 to 30 red knots in the spring.

New Jersey's Joe Lomacks did. Thousands were along the shores of Delaware Bay.

In 2001, Niles found the Arctic nesting grounds by outfitting a few Delaware Bay birds with radio transmitters that were audible for only a short distance. Up in the Arctic, he hired a small plane to crisscross the rocky terrain until he finally heard faint beeps through the antenna. They were on an island in Hudson Bay.

Less than a decade later, the birds were being fitted with tiny data loggers that would record where they were every day. Scientists' jaws dropped when they realized that some of these birds detoured hundreds of miles to avoid storms, but still survived and kept going.

Hoose includes profiles of the scientists - ostensibly so that young readers will have role models. But who wouldn't love reading about Clive Minton, who spent much of his life perfecting the science of catching shorebirds? It was he who developed the cannon net - a net attached to a projectile and shot over a flock of birds.

Or New Jersey's Amanda Dey, who always wanted to be a wildlife biologist? Lacking confidence, she became a secretary. But when she turned 27, she enrolled in college. "I'll tell you," she says, "if you hold a shorebird in your hand only one time, you are changed forever."

Holding this book in your hands isn't quite the same thing, to be sure. But it comes mighty close.

B95's story - and that of his brethren - is both tragic and triumphant, and who's to say how it will end?

In 2010, researchers feared B95 was gone. They hadn't seen him for almost a year.

Then, on Aug. 19, Canadian ornithologist Yves Aubry spotted a group of red knots feeding in the Mingan Archipelago in Quebec - another recently discovered stopover.

"Aubry could tiptoe close enough to tell that most had adult plumage, but he couldn't quite see if they were banded," Hoose writes with his characteristic flair for storytelling.

"They kept moving. He kept moving. And then, for a long moment, they settled in one spot. Aubry tightened the focus in his eyepiece."

At 4:51 p.m., an exultant e-mail spread around the globe: "B95 is alive!"

Scientists figured he was at least 18 years old. "How do you explain something like that?" Aubry later said. "Maybe you can't. . . . Maybe it's just enough to know that there is such an athlete among the animals of earth."

This spring, Hoose's book was finished when researchers once again arrived on Delaware Bay.

It seemed against all odds that they'd spot B95. "Nothing lives forever," they told themselves.

But on May 28, as she scanned a flock with her scope, Argentine researcher Patricia Gonzalez gave a little cry. There was B95, right on the beach in front of her.