Survival of whooping cranes hinges on financial decisions

Figure 5. Two adults and one juvenile whooping crane spotted during aerial survey on Wood Buffalo National Park, Canada. Photo: John McKinnon / ©Parks Canada /Wood Buffalo National Park.
Two adults and one juvenile whooping crane. Photo: John McKinnon / ©Parks Canada /Wood Buffalo National Park.

The Victoria Advocate
By Sara Sneath
April 11, 2015 at 10:21 p.m.

Researchers have spent 40 years and millions of dollars trying to recover the whooping crane.

Much of that time and money was spent trying to introduce a new population of the endangered birds to the U.S. But after four decades, none of the flocks have become self-sustaining. Without researchers continually hatching eggs in captivity and releasing them in the wild, the flocks would likely die off.

During the same period, the only remaining wild flock, which winters near Aransas National Wildlife Refuge and has started its annual migration back to Wood Buffalo Park in Canada, has more than quadrupled.

The biggest obstacle facing the wild flock is the need for protected coastal marsh habitat in Texas, where the birds spend about seven months of the year. With just more than 300 birds, about half of the population winters on private land.

Setting aside enough land for one pair of the territorial birds could cost as much as $1 million. And with limited resources, researchers must decide whether they should continue to devote funds to reintroduction efforts elsewhere or start investing more in the only existing wild flock and the only flock reproducing on its own.

“The wild flock is by far the best hope that we have, and we are not putting enough emphasis on them at this time. And we need to,” said Chester McConnell, a retired wildlife biologist and co-founder of Friends of the Wild Whoopers.

Without any deadlines placed on ongoing efforts to create another flock, researchers are hesitant to throw away projects in which they have invested more than a decade of work and millions of dollars.

But the decision isn’t up to researchers alone. Private donors who have fallen in love with the iconic species and its struggle for survival have helped fund reintroduction efforts. They, too, are deciding where to invest their hope in the tallest bird in North America.

The Insurance policy

Whooping cranes were largely wiped out by habitat loss and hunting. In North America, where giant animals such as giraffes and rhinoceroses aren’t present on the landscape, the 5-foot-tall white birds are like dinosaurs. And, with beady yellow eyes and skinny black legs, they look every bit as prehistoric.

The population of giant birds plummeted to about 20 birds in the 1940s, according to the latest International Recovery Plan for the Whooping Crane dated 2007.

In 1970, the U.S. Fish and Wildlife Service listed the cranes as endangered. The only birds left were those in the Aransas-Wood Buffalo flock.

A pervading thought began: With a small population of whooping cranes all in one location, a single hurricane, oil spill or other catastrophe would wipe out the population.

Since the ’70s, researchers have tried to create a flock of whooping cranes that is capable of surviving and reproducing on their own. So far, it hasn’t worked.

It takes a minimum of 10 years before scientists can judge whether a project to reintroduce whooping cranes is working, said U.S. whooping crane recovery coordinator Wade Harrell of the U.S. Fish and Wildlife Service.

The birds don’t reach sexual maturity until they’re about 4 years old. Once mature, pairs lay two eggs, and typically only one of the chicks survives.

“Whooping cranes are slow breeders,” Harrell said. “It wears on our patience.”

Researchers have abandoned two reintroduction attempts that lasted more than a decade each.

And, an ongoing effort to build an Eastern migratory flock of whooping cranes is in its 14th year.

Another effort to create a nonmigratory flock in Louisiana started about four years ago.

Despite decades of work, researchers have been unable to create a self-sustaining flock of whoopers. But that shouldn’t overshadow the progress that has been made, said Barry Hartup, a co-chair of the Whooping Crane Eastern Partnership Guidance Team and veterinarian with the International Crane Foundation.

Measure of success

Engineering a flock of whooping cranes requires molding every detail, without leaving a fingerprint.

Birds in the eastern migratory flock were hatched in a zoo-like setting, raised by humans in whooping crane costumes and taught to migrate with an ultra light aircraft, all the while trying to keep the birds wild and unfamiliar with humans.

Despite the largely artificial process by which the birds were raised, the eastern migratory flock has made more progress than past reintroduction efforts, Hartup said.

“It’s a success story because this is the furthest that anybody has gotten with any crane species,” he said.

There are about 100 birds in the eastern population, which has a survival rate near the only wild flock, Hartup said.

The birds are pairing up, breeding and laying eggs. But the cranes tend to abandon their nests before the eggs are hatched.

The abandonments happen within days of one another, which has led researchers to believe there is something in the environment causing birds to leave behind their eggs. Observations at Necedah National Wildlife Refuge in Wisconsin, where the birds were released and come back to nest, found that the cranes were bombarded with biting black flies.

“They’re doing all the right things, except we can’t seem to get them over the hump of their nesting because of this one parasitic fly that nobody had ever drawn a connection to ever before in history,” Hartup said. “It was just kind of bad luck.”

In 2011 and 2012, researchers applied Bacillus thuringiensis israelensis, a naturally occurring soil bacterium – also known as Bti – which targets biting insects, to tamp down the population of black flies. While a handful of chicks hatched, only two survived.

The Bti treatments got the birds to sit on the nests longer, but it didn’t prove successful in fledging more chicks, said Peter Fasbender, Hartup’s co-chair of the Whooping Crane Eastern Partnership Guidance Team.

“There is still something acting on this population,” he said. “We could continue to apply Bti every year, but we’re still not going to get at the question of why birds aren’t fledging.”

Not being able to reproduce birds in the wild is costly.

In 2011, researchers estimated that the cost of raising, training and teaching one bird to migrate was $113,886, according to a cost summary provided by Harrell.

Because only a handful of birds have fledged in the wild, building up the eastern migratory flock population has pulled from the limited number of captive flock eggs. And with a new reintroduction effort underway in Louisiana, since 2011, the two projects have had to split the estimated 30 eggs produced by captive birds every year.

The split could mean neither project is getting enough eggs for a viable reintroduction attempt, according to the International Recovery Plan.

“It is obvious from all scenarios modeled that egg transplants of less than 30 eggs per year will not suffice to establish a self-sustaining population in a reasonable period of time,” according to the report. “Natural breeding will be essential to establish a self-sustaining population.”

Food for thought

Last month, whooping crane recovery decision-makers met with wildlife experts from around the world who have successfully reintroduced endangered species. During the meet-up, at the International Crane Foundation headquarters in Wisconsin, researchers mulled over what could be at the root of the Wisconsin population’s problem with raising their young, Fasbender said.

One thought widely discussed was the amount of food available to the birds as they incubate, hatch and rear chicks. The marshlands of Necedah National Wildlife Refuge are sandy, with a lower nutrient level. And while 70 birds still head to Necedah every year to nest, cohorts of birds since 2011 were released farther east, where not only are there fewer black flies, but the soil is thicker and more nutrient rich.

The thought is that more nutrient rich soil produces more nutrient rich plants and continues up the food chain.

But the birds released farther east are just starting to reach sexual maturity. So, it’s too soon to tell whether the environment will be more conducive to reproduction, Fasbender said.

The rich habitat of Louisiana wetlands has been a big reason why researchers are more hopeful of the nonmigratory reintroduction effort there, said Bob Love, Louisiana Department of Wildlife and Fisheries Coastal and Nongame Resources administrator.

The landscape has been altered all over the U.S. since whooping cranes were in their prime. In particular, wetlands have been drained and minimized, Love said.

But in Louisiana, a form of aquaculture has taken over in which fields flooded with freshwater for rice are also used to grow crawfish. The result is a food-bountiful habitat for whooping cranes.

“Man has altered all of those wetlands. But in Louisiana, man has created working wetlands that are beneficial. With this aquaculture the water depth is perfect for them and it’s producing a crawfish that those birds love,” Love said. “The Louisiana habitat base may provide answers that the recovery of the whooping crane needed for success.”

But the Louisiana population is too young to have viable eggs. While a pair has nested two years in a row, the clutches have been infertile, a common predicament of birds nearing sexual maturity.

Meanwhile, researchers have tried to find more cost-effective ways to sustain the eastern migratory population. The flock will stop using captive eggs in the next two years, Fasbender said.

“We’re getting close to the numerical threshold population we wanted in that 100-bird population. We’re there. We’d really like it if it were self-sustaining,” he said. “But we’re not going to keep supplanting eggs to this population.”

Researchers are also looking at methods other than the ultralight aircraft, which inspired the movie “Fly Away Home,” to teach birds to migrate.

Groups of young birds have been directly released into areas of Wisconsin near adult whooping cranes and sandhill cranes in hopes the young will follow the older birds on their migration south. And, more recently, individual chicks were released near chick-less pairs of whooping cranes. The hope is the adult cranes will tolerate the young birds’ presence as they learn survival skills and migration from the older birds, Hartup said.

“A lot of these adults are ones who attempted nesting and couldn’t quite finish it. And then later in the season, they see this chick. They groove on it. They tolerate it. And they allow it to hang with them,” Hartup said. “The idea is that they come to gain safety and knowledge through this loose social bond they create.”

The alternative introduction technique may also address the poor parenting skills exhibited in the flock, as the birds are taught whooping crane behavior by another whooper, instead of a human dressed as one.

Birds of a feather

But some believe the reproduction problem with birds hatched from captive flocks is ingrained from decades of handling by humans, in a process known as “captive selection.”

The idea is that birds able to survive in captivity long term are less wild, said Felipe Chavez-Ramirez, director of conservation programs for the Gulf Coast Bird Observatory.

“So, over generations you get these birds that are adapted to captivity, that stress out less, that are less concerned with their surrounding environment, and those are the birds you’re putting back into the wild,” he said. “When you send them back into the wild, you hope you’re putting out wild organisms, but if these guys think they’re more of a caged bird, well then they’re not going to respond as well to threats, such as predators.”

While it’s not yet clear whether captive selection is affecting reintroduced flocks of whooping cranes, some researchers have suggested taking eggs from the wild flock to test the theory. The recovery team, which provides overall recovery objectives and strategies, is on board with the idea, Hartup said.

But taking eggs from the wild nests could once again pit the needs of the only self-sustaining flock against those of the reintroduced flocks.

While typically only one chick is raised from the two eggs the birds lay, the second egg provides a sort of insurance policy, Chavez-Ramirez said. And in some cases, both chicks survive.

Two sets of rust-colored twin chicks were spotted at the Aransas refuge this year. Bird lovers were able to watch both sets grow up over the winter, losing their rust color to the white plumage of adulthood.

Two studies have been conducted on whether taking an egg from wild nests affects long-term population growth. The studies showed conflicting results, Chavez-Ramirez said.

Private citizens, who have tried to bring attention to the wild flock of whooping cranes, are adamantly against the idea of putting wild bird eggs under reintroduced birds that were hatched in captivity.

“If you put a tame egg under them or a wild egg under them, they still aren’t going to know what to do. There’s nothing that’s going to seep out of that egg shell into their brain to teach them how to be parents,” said McConnell, the retired wildlife biologist and co-founder of Friends of the Wild Whoopers. “I want them to keep trying, but I don’t want them to use the Wood Buffalo eggs to try.”

McConnell, and his co-founder Pam Bates, are behind an effort to invest in easements of land for habitat for the wild flock, an idea they hope more will buy into.

Purchasing land to support the wild birds costs about $2,000 an acre. But it’s a one-time cost, versus the annual costs associated with hatching and releasing birds that cannot reproduce on their own.

While the reintroduction efforts are awe-inspiring, no effort to reintroduce a species of cranes has ever worked, Chavez-Ramirez said.

“We have a population that’s survived on its own. All we have to do is help it continue to do that, to facilitate what it already has, and it might be more cost-effective that way,” he said. “So a dollar could go further if we do that versus trying to start a whole other population in a whole other place, especially now that we have a track record of not being able to do it yet. It seems like a very difficult task that may or may not be possible.”

To read Sara Sneath’s article in the Victoria Advocate’s website, click here. logo

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