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 DALLAS — The world's last remaining natural flock of endangered whooping cranes, which suffered a record number of deaths last year, will probably see another die-off because of scarce food supplies at its Texas nesting grounds this winter, wildlife managers said.

The flock lost 23 birds in the 2008-2009 winter season, in part because its main source of sustenance, the blue crab, all but vanished from drought-parched southern Texas. The rains eventually came, but they were too late to produce healthy amounts of blue crabs for this winter.

"We're looking at a pretty slender year, prey-wise, and it's going to make the cranes work harder to get food," said Allan Strand, field supervisor for the U.S. Fish and Wildlife Service in South Texas. "I feel that we're probably going to have a die-off. It's conceivable that we could have a significant die-off."

The whooping crane, the tallest bird in North America at about 5 feet, was nearly extinct in 1941 before making a steady comeback. There are three flocks now, but the one that travels 2,400 miles each fall from Canada to the Texas Gulf Coast is the only one that migrates without human help.

According to the most recent aerial survey, there are an estimated 263 birds in the Texas flock. The survey, conducted last week, found that one chick has already died and another was missing.

It's normal for one crane to die in the average November-to-March winter season, and last year's 23 deaths were the most since 1938 when the wildlife service began tracking cranes at the Aransas National Wildlife Refuge near Corpus Christi.

Also in last week's survey, Tom Stehn, the wildlife service's whooping crane coordinator, noted some birds were already leaving the marshlands to search for food elsewhere. An extended hunt for food would burn more important energy that the cranes need to survive the lean winter months, he said.

The crabs are loaded with fat and calories, and an adult whooping crane can eat up to 80 a day. But when their crab count is down, the cranes can end up in bad shape, particularly after the draining migration from Canada, Strand said. Last year the flock's hatch was down about one-third, and "that's a direct correlation to the birds' health when they get back," he said.

The cranes face other challenges. They are losing habitat to housing developments that draw even more water out of their nesting grounds along the Guadalupe and San Antonio rivers.

Last month, a conservation group filed paperwork to sue state regulators, alleging they allowed too much water to be taken from the rivers during the crane wintering season. That overuse increased the salinity of inland waters, hurting the birds' water and food supplies, the group said.

The wildlife refuge has requested permission to put out calorie-rich "crane chow," the same kind of food the birds eat in zoos. Even if they are allowed to do that, there is no guarantee of success.

The cranes generally nest in pairs or as a couple with one juvenile spread out along a 30-mile coastline. Even if the food distributors correctly target the birds, there is no guarantee they will eat the chow.

Some experts disagree with supplemental feeding, but Strand said it might be necessary.

"The cranes are not a viable population," he said Tuesday. "They can't support themselves. I hate to think if we don't do it and we lose another 30 or 40 cranes this year, I don't know how we're going to explain it."

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On the Net:

Aransas National Wildlife Refuge: http://www.fws.gov/southwest/refuges/texas/aransas

So many species in trouble, it's so sad.

This winter will be a hard one for the whooping crane, one of the most endangered species in the world. The last remaining natural flock of the rare birds took a devastating loss last year at its wintering grounds at the Aransas Natural Wildlife Refuge. The flock lost 23 birds, a heavy blow to a species that only counts an estimated 263.

This November-to-March wintering season is expected to be just as hard on the big birds. At about 5 feet, they are the tallest in North America.

The immediate cause of last winter’s die-off was the scarcity of blue crabs, the chief source of food for the birds during their time along the Gulf Coast. But some environmentalists believe the real cause is far upstream from the coastal marshes where the birds winter.

In December, a coalition of environmentalists filed paperwork in preparation to suing the state, alleging that regulators have allowed too much water to be taken out of the Guadalupe-Blanco river watershed, to the detriment of the cranes. Developers of subdivisions, industry operators and agricultural interests far from the Gulf Coast — the Guadalupe-Blanco watershed includes parts of the Hill Country may not think of their own water needs as competing with the water demands of whooping cranes. But the survival of the species is connected with the health of the river.

In Texas, where the demand for water is ever increasing from growing cities and suburbs, guarding the downstream flow of rivers is often a thankless task. Even though the Legislature has mandated that river authorities set aside freshwater flows for wildlife needs, to much of the public, water that is allowed to be released from upstream reservoirs is “wasted.” Even in Corpus Christi, whose tourist industry depends heavily on a healthy coastal environment, the release of freshwater from the city’s reservoir at Choke Canyon is still disputed in some quarters. But the necessity of protecting downstream flows is becoming ever clearer as underlined by the stress being placed on the last surviving members of a magnificent species.

Which is not to say that the allegations in the suit will be easy to prove. The scarcity of blue crabs came after one of the hardest droughts in South Texas history. The drought placed stress on every species in the region. And the blue crabs, which help the birds restore their strength from the long migration from Canada, still haven’t come back in the numbers necessary to feed the birds. Some of the big birds already have begun foraging outside the refuge boundaries, using up more of their energy just in finding enough food. Refuge officials have plans to put out food, the same kind that cranes in zoos are fed. But that may not be the answer for a flock that naturally feeds on the rich food of blue crabs.

Defendants in any lawsuit can well point out that the whooping cranes, despite being few in number, have actually increased since their low point in 1941 when only a handful existed. But the species is still in a precarious position. “I feel that we’re probably going to have a die-off,” Allan Strand, field supervisor for the U.S. Fish and Wildlife Service in South Texas, said last week. “It’s conceivable that we could have a significant die-off.”

The species has been hit hard by a drought, a natural occurrence in South Texas. But the big birds’ situation shouldn’t be made worse by being squeezed out of their share of freshwater river flows, if the evidence says that is happening.

Eight endangered whooping cranes — roughly 7 percent of their wild population in the eastern United States — have taken up residence in eastern Jefferson County.

The arrival of these rare, large birds — they stand 5 feet tall with wingspans of 7 feet — has delighted Louisville conservationists and bird-watchers who have seen them.

But the birds' choice to roost in an urban area has also triggered concerns for their safety and calls for people to leave them alone.

“We want to keep the birds as safe as possible,” said Eva Szyszkoski, who tracks cranes for the International Crane Foundation, a partner in a national crane recovery project. “We want to keep people as safe as possible.”

Seven of the eight birds are less than a year old and on their first migration from Wisconsin, she said. Because they are young and impressionable, they are more susceptible to becoming overly accustomed to people, she said.

They could be drawn in too close to homes, businesses or roads, and the threats posed by people, pets, cars, trucks or industrial activities.

Officials say each exposure to humans lessens the whooping cranes' fear of people, an important survival mechanism. In raising the juveniles, biologists, veterinarians and others go to extreme lengths — including wearing costumes around the birds and not talking — to try to keep them wild.

Crane advocates are especially sensitive now, because the wild population has fallen off in recent years. There's been a food shortage in the West, and a storm in Florida killed 17 in 2007.

Authorities are still looking for someone in southwestern Indiana who last fall shot and killed the only wild female crane in the eastern United States that had been successfully reproducing.

“This was a terrible loss for our population,” Szyszkoski said.

The wild population, as of last count, is about 260, she said. Of those, as many as 105 are living in the eastern United States. There were just 16 in 1950, according to federal biologists.

Since 2001, Operation Migration, another member of the whooping crane partnership, has led small flocks of juvenile birds, using ultralight aircraft and pilots dressed as birds, on their first migration from Wisconsin to Florida, so they can learn the route.

“This was a terrible loss for our population,” Szyszkoski said.

The wild population, as of last count, is about 260, she said. Of those, as many as 105 are living in the eastern United States. There were just 16 in 1950, according to federal biologists.

The group in Louisville is part of another strategy, where young birds are paired with adults who have made the trip before, said Tom MacKenzie, the regional U.S. Fish and Wildlife Service spokesman based in Atlanta.

Not all cranes on their own go all the way to Florida. This group went as far south as Chattanooga, Tenn., then turned back.

One early morning last week, the birds stood together in a large wheat field illuminated by a low-hanging moon and the early light of dawn. A small group of bird-watchers with spotting scopes and cameras observed them at a safe distance as they began to stretch their legs and wings.

“It's so neat they would choose Jefferson County as their overwintering grounds,” said a bundled up Jane Bell, past president of the Beckham Bird Club.


Because they appear to get their needs met here, she said she thinks they might come back next year.

“Birds, like people, are creatures of habit,” she said.

The bird-watchers included Jeff Frank, executive director of Future Fund Inc., a group working to save open spaces in the area. He said he first heard about the cranes more than two weeks ago when a friend called to say he thought he had seen “giant snow geese.”

Frank has been watching the cranes on and off. He called them “some of the most extensively monitored and protected birds in the nation,” noting that some are equipped with devices that allow biologists to pinpoint their location via satellite.

Future Fund, the Beckham Bird Club and other birding groups urged their members and others to avoid telling anyone where to find them. “The birds are using private lands with no public access,” Frank said.

The U.S. Fish and Wildlife Service also asked The Courier-Journal to avoid describing their precise location.

“If you end up with 50 people out there, their lives could be in danger,” MacKenzie said.

At the same time, officials acknowledged it's hard to keep a secret of such spectacular birds, the tallest in North America. And Frank said it says something good about Louisville that there's apparently enough nature left to sustain them.

Officials don't know what's next for the cranes in Jefferson County, but some speculated they may be waiting for the weather to warm to fly north to the Muscatatuck National Wildlife Refuge in Indiana.

Back at the wheat field, at 7:57 a.m., with the sun almost shining, the eight sprung from their long legs and took flight, soaring over the farm then heading north and out of sight.

“Oh my,” Bell said. “There they go, above the tree line. Isn't that neat.”