Aransas National Wildlife Refuge — After the poisonous snake slithered into the whooping crane family's marshy grounds and sank its fangs into the chick's neck, death seemed certain.

The bird's head quickly turned red and swelled to the size of a basketball. He refused to eat for days and was too weak to even stand. Somehow, though, he survived.

And now the bird — dubbed Scarbaby — is a healthy adult whose resilience offers a speck of hope for the endangered species. Just a year after a record number of cranes died in their south Texas wintering grounds, wildlife managers embrace even the smallest successes.

"To me, it symbolizes the fight to survive," said Tom Stehn, a U.S. Fish and Wildlife Service biologist who's studied them for nearly 30 years. "They're pretty tough."

There are about 400 wild whooping cranes in the world, and biologists had feared that number would drop further this winter after last year's record 23 Texas deaths. Even though the birds fared better than expected — only one died this winter — the cranes face many obstacles to survive as a species.

They've got a 2,500-mile migration back to Canada later this month, food and water shortages could take their toll, and then there's the usual hazards of deadly power lines and encroaching development. Last year, 34 cranes died after spring.

"We don't really know how strong they are, how much body fat they have and how they'll do on the migration north," said Ron Outen, director of conservation group The Aransas Project.

Scarbaby's flock of 264 birds is the world's only group of naturally migrating whooping cranes. Conservationists say it is the species' best chance for survival because it's self-sustaining. The flock spends its winters at the Aransas National Wildlife Refuge near Corpus Christi.

There's another flock in Wisconsin that is guided by an ultralight aircraft on migrations to and from Florida. A third flock in Florida is small and doesn't migrate.

The cranes — the tallest birds in North America at about 5½ feet — have made a remarkable comeback from just 15 birds in 1941. Yet experts see disaster ahead.

"I've been screaming for about 10 years now that they're walking toward a cliff," Stehn said. "The birds are fighting like crazy. They're doing everything they can. It's really just if man can leave them alone."

In Texas, one of the biggest concerns is the prospect of more drought. Last season's brutally dry conditions left cranes without enough crabs and water.

The Aransas Project has sued the state over the 23 crane deaths. The group alleges Texas allows too much water to be drawn from rivers, which could lead recurring drought conditions and more bird deaths.

The state environmental agency isn't commenting on the lawsuit, but has defended its processes for allocating river water.

Stehn says if the waterways aren't viable, the flock will die.

A similarly bleak outlook was predicted for Scarbaby in 2005, when the deadly snake bit him.

Tommy Moore, a birding tour boat captain who saw the drama unfold over, remembers watching the bird collapse again and again into the shallow water. Biologists were so worried about Scarbaby, Stehn formed a team to check on him.



Soon, Scarbaby was nibbling on crab chunks and even caught one. Whooping cranes migrate in family units, but once Scarbaby started eating his parents took off for Canada without him. He did fine in Texas, though, taking up with other young birds that stayed behind.



Aside from a small scar on his neck, Scarbaby looked perfectly healthy one recent afternoon. He posed and preened for a packed tour boat before flying overhead to bird lovers' "oohs," ''aahs" and clicking cameras.



"It's really a cool story," said Moore, a gruff character who was so touched by Scarbaby's ordeal he wrote a children's book about it. "The way I look at it, it means that's one tough bird."