Revealing the
Blue-Footed Booby's
True Colors

NORTH SEYMOUR ISLAND, Galapagos — The birds move with comic grace, like Fred Astaire and Judy Garland as hobo swells in oversize shoes. The male faces the female and slowly, slowly lifts up one foot, sets it down and lifts the other.

Check out my feet! They're blue. Really, really blue.

The female mirrors his ponderous moves.

Mine are blue, too. Is this ground sticky, or what?

He leans over, spreads his wings wide, points his bill at the sky and whistles breathily, as if blowing on a toy flute. She grunts and totters up to him, and they clack bills. He grabs a pebble, and they clack bills again; he drops the pebble and spears a twig. Clack, whistle, grunt, whistle. And suddenly, she backs away.

Desperate, the male solemnly starts high-stepping again, displaying his beautiful teal-blue feet. But the courtship has fizzled, and when the female again lifts up a foot in response, it looks as if she's waving goodbye.

It's dating time here for the blue-footed booby.

Everywhere, dozens of times a day, the large, handsome seabirds are making their highly ritualized courtship display - one reason the boobies are among the most celebrated and beloved residents of this archipelago.

They are also feeding voraciously and spectacularly, circling high over the water, alert for the slightest flicker of fish, and then freezing in midair for a fraction of a second before dropping headfirst onto their targets, like missiles falling from a plane.

They squabble with one another over territory and nesting sites. They dodge parasitic frigate birds with red-balloon crops that pluck at the boobies' tails and try to force them to regurgitate freshly caught fish but mostly fail.

On the Galapagos and on Isla Isabel, a Mexican national park south of the coast of Baja, blue-footed boobies have no real predators to fear or human hunters to shun, and as a result they live proud, public lives. That openness and accessibility, beyond captivating tourists, have proved a bonanza for scientists, too.

Research teams from Mexico and the United States have followed populations of the long-lived birds for years, even decades, and they have gathered a wealth of insights into the deep nature of being Sula nebouxii: how boobies choose and lose mates, the shifting allure of fidelity versus adultery, the measured brutality of older siblings, the contingency of parental love and the reason behind the boobies' fetish for feet.

"They're superfascinating animals and such a good research model," said David J. Anderson of Wake Forest University in Winston-Salem, N.C., who studies both the blue-footed booby and the related Nazca booby. "They let you move among them without minding too much. You try to do that with a continental bird or mammal - forget about it. But with these guys you see it all."

In one discovery that subverted expectations, Oscar Sanchez Macouzet and Hugh Drummond of the National Autonomous University of Mexico and their colleagues determined that boobies subjected to severe bullying and abuse as nestlings suffered few consequences as adults.

No matter how relentlessly the birds had been pecked at and bitten by older siblings, no matter how often food had been snatched from their beaks or how slowly they had grown, on reaching maturity the once-persecuted birds proved surprisingly confident, capable — unflappable. They were able to attract partners, repel rivals and raise families as successfully as their domineering peers.

"Bullying in infancy does not make wimpy adults," Dr. Sanchez Macouzet said.

While many boobies change partners from season to season, there are great benefits of long-term fidelity, researchers have found. Comparing the breeding success of pairs that had been together for years with that of similarly mature boobies that had recently repartnered, scientists determined that the established pairs reared 35 percent more offspring to fledglinghood compared with the new mates.

And in new findings that will be published soon — and are enough to turn this working mother's feet cerulean — scientists have discovered that the key to a successful long-term booby partnership is the equitable sharing of nest duties year after year.

Biparental care is the rule among boobies, but longtime mates have perfected the art of symmetry and turn-taking. They spend the same time brooding and feeding the young, and expend the same physical effort as seen in measures of blood cells and body mass.

Such egalitarian couples, said Dr. Sanchez Macouzet, "have reached the sweet spot of cooperation, compatibility and a willingness to avoid the exploitation of your partner."

Dr. Drummond and his colleagues have also identified another booby mating pattern that seems to work nearly as well as a stable long-term partnership and in some ways contradicts it: the May-December effect.

For reasons that remain mysterious, Dr. Drummond said, booby couples in which one bird is young and the other old often have greater breeding success compared with pairs of the same age.

Analyzing the outcomes of 3,361 booby offspring, the researchers found that the chicks of age-mismatched parents were significantly more likely to later become parents themselves compared with the progeny of similarly aged pairs. It didn't matter whether the mother was younger than the father or vice versa.

"The advantage to the chicks was the same either way," Dr. Drummond said.

"Life is complicated," he added, "and every year boobies are conjuring with several different variables when making their choice among partners."