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  Whoopers

by Dave Yanko

Wild things are truly alive only in the place where they belong. Away from that place they may bloom like exotics, but the eye will search beyond them for their lost home. - J. A. Baker in The Peregrine

-- courtesy U.S. Wildlife Service
 

Around April of each year, the world's single surviving flock of migrating whooping cranes trickles out of Aransas National Wildlife Refuge on the Gulf of Mexico and heads north on a 2,500-mile journey to its summer nesting grounds in northern Canada.

At the juncture of Alberta and the Northwest Territories in remote Wood Buffalo National Park, 40 to 50 breeding pairs of whoopers perform an annual dance of renewal that typically produces two eggs per nest. However, predation, drought, brutal sibling rivalry and, until recently, human intervention meant the flock was fortunate to return to its wintering grounds with perhaps 20, rust-colored fledglings.

While more than 100 whoopers exist in captivity at several locations around North America, this small, wild flock is the last remaining example of migrating whooping cranes in their traditional habitat. It's a blessing the mortality rate of older birds tends to be lower than the survival rate of new ones. From a population of only 15 birds in 1941, the flock in late 1997 registered 182 members during the annual count at its wintering grounds in Aransas, Texas. It would seem the whooping crane, majestic icon of North American conservationists, is gaining a toehold on perpetuity.

"Last year was a record year," Brian Johns, a Canadian Wildlife Service biologist and Canadian coordinator of the Canada/US whooping crane recovery team, said in a June 1998 interview. "There were 51 nests -- a new record -- and about 58 young that hatched in June. Thirty of those survived the summer and arrived on the wintering grounds.

"There were only 10 adults and sub-adults that died last year. So the population went up by 20."

But Johns and his whooper colleagues aren't reaching for the champagne yet. There remain several thresholds to cross before the international recovery team sees the whooping crane downlisted to "threatened' from "endangered'. The first is stability.

"The recovery plan says we need to have a minimum of 40 breeding pairs. But to make sure the population is stable, we'd like to have 40 breeding pairs for a minimum of 10 years."

The number of breeding pairs in Wood Buffalo sank to 28 in 1994, after reaching 45 in the previous year. The pairs were there, Johns explains, it's just that many of them didn't nest.

The shallow bogs and rugged terrain of Wood Buffalo National Park, breeding grounds for the Wood Buffalo/Aransas flock.
-- courtesy Canadian Wildlife Service
The shallow bogs and rugged terrain of Wood Buffalo National Park, breeding grounds for the Wood Buffalo/Aransas flock.

Whoopers are omnivores, but they have strong preferences. In the coastal marshlands of Aransas, their favorite food is the blue crab. During the winter of 1993-94, the crabs didn't move into the marshes until the flock began its northern migration.

"We suspect some of the birds just weren't in very good shape when they got here," Johns said from his seasonal office in Fort Smith, Northwest Territories, located adjacent to Wood Buffalo National Park. "Some of them just decided not to nest."

In the four years from 1995 to 1998, nesting pairs numbered 49, 45, 51 and 47, respectively. But the 1994 glitch aptly demonstrates why Canadian and American biologists remain cautious about the long-term viability of the migratory flock: any number of potential natural and man-made disasters continue to threaten it.

U.S. President Franklin Delano Roosevelt recognized this back in 1937, when he decreed Aransas a national wildlife refuge for the flock of whooping cranes that traditionally wintered in the marshlands and shallow bay areas of the Texas gulf. In 1940, the non-migratory remnant of a flock that once nested in Manitoba was reduced to six from 13 birds by a hurricane that hit its home in Louisiana. The last remaining member of that flock, a bird that came to be known as "Mac", was taken into captivity in 1950 and died six months later.

In spite of its protected status and the dedicated work of conservationists, however, Aransas poses a host of threats to its wintering residents: hurricanes are no less common in southern Texas than in neighboring Louisiana; marine food resources can be scarce, contaminated or simply unavailable when storms raise water levels in tidal marshes; and traffic on the Gulf Intracoastal Waterway that cuts through the southern portion of Aransas is among the heaviest on any waterway in the world. Much of that shipping is petrochemical barges that not only threaten spills but erode precious shoreline in their wake.

The Wood Buffalo nesting grounds are much more remote. In fact, they were weren't even discovered until 1954. It's only by fortunate coincidence the region where the whoopers breed is within an area set aside as a national park in 1922 in order to protect the wood bison who inhabit the area.

Wood Buffalo's remote location reduces human threats to the flock -- permits are required to visit the nesting area. But water levels vary from year to year, and drier years bring reduced chick survival. And there's always disease and predators lurking in the wings.

Whooping crane fledglings must be strong enough to handle the long southern migration.
-- courtesy Canadian Wildlife Service
Whooping crane fledglings must be strong enough to handle the long southern migration.

"There was a set of twins we saw two days ago, and the next day both of them were gone," Johns said. "We don't know whether it was bear or wolf, but something picked them off."

Given the threats facing the Wood Buffalo/Aransas flock, the whooping crane recovery plan also calls for the establishment of two additional breeding flocks with 25 breeding pairs in each. And here, efforts to date have brought disappointing results.

In 1975, Canadian and America biologists began collecting one of two eggs from many Wood Buffalo nests and placing them in sandhill crane nests at Grays Lake National Wildlife Refuge in Idaho. They hoped the sandhills would hatch the eggs, rear the young whoopers and teach them the migration route to the sandhills' wintering ground in New Mexico. This worked fairly well.

But the whoopers, who don't reach sexual maturity until three to five years of age, imprinted upon the sandhills and never formed breeding pairs. The initially-promising experiment was scuppered in 1996 (thereby contributing to the bumper crop of chicks at Wood Buffalo the next year) and there's now ('98) only two whoopers in the so-called "Rocky Mountain" flock.

At Kissimmee Prairie, Florida, a group of 14 cranes reared in captivity was released early in 1993 in an attempt to establish a wild, non-migratory and self-sustaining flock in the south-central portion of the state. More young birds were released in following years. But bobcats have ravaged the youngsters, who are fending for themselves without benefit of parental guidance. And so far, no breeding has occurred.

"We had high hopes they were going to start breeding two years ago. . . and last year. . . and this year," says Johns. "Some pairs have built nests, but none have laid any eggs yet. There's still hope there."

There's hope, as well, in two 1997 studies involving the use of ultra-light aircraft to teach birds born in captivity the migratory routes appropriate to their species. This "Fly Away Home" method delivered promising results in an experiment involving a group of sandhill cranes raised in the Ontario wilderness and later led by plane to Virginia. Another study employed an ultra-light to lead a mixed flock of sandhills and whoopers from Idaho to New Mexico.

Whoopers winter at Aransas National Wildlife Refuge, on the Texas gulf.
-- courtesy U.S. Wildlife Service
Whoopers winter at Aransas National Wildlife Refuge, on the Texas gulf.

In both cases, says Johns, the birds followed the ultra-lights to the wintering grounds, wintered well among their wild counterparts, and then migrated in the spring to within 80 kms (50 miles) of where they were raised.

On the down side, the effects of human intervention continue to nag these reintroduction experiments. Imprinting problems occurred even in the Ontario study, where the young sandhills were handled by people wearing crane costumes.

"(Some sandhills) ended up in several school yards, a soccer field. . . where there were kids and voices and human activity," Johns said. "Now, they've got a much stricter protocol around the cranes. There's no talking at all, so they don't get use to human voices.

"They want them to be wild. But they don't want them to be so wild they won't follow the ultra-light."

The grand scheme behind the ultra-light experiments is the creation of a second, wild, breeding, migratory flock of whooping cranes in North America. Studies are underway to find suitable nesting and wintering grounds for this proposed new flock which, with the non-migratory Kissimmee flock, could meet the downlisting criterion of two additional, self-sustaining communities of whooping cranes.

Wintering grounds will be on the gulf coast, either Louisiana or Florida. Saskatchewan, in the middle of the migration corridor for the Wood Buffalo flock and an important staging area during southern migration, was an early contender as the northern nesting grounds of this proposed flock. But biologists now think that would be a mistake.

"We'd want to keep the flocks separate so that if something happened to one of them, the other wouldn't be affected," says Johns. "If we did want some genetic material to be mixed, we could move eggs at some time in the future."

The inter-lake region of Manitoba, located north of Winnipeg between lakes Winnipeg and Manitoba, is now being studied as the proposed northern nesting grounds for this would-be flock, although some would like to see the nesting grounds located in the north-eastern U.S. Both areas fall within the former nesting range of the whooping crane.

The search continues for a natural home.
-- courtesy U.S. Wildlife Service
The search continues for a natural home.

But all former habitats have changed to one degree or another. That's much the reason why whooping cranes came to the brink of extinction in first place. Human intervention remains their best hope for survival, and their biggest obstacle.


For a story about viewing whooping cranes during the Saskatchewan leg of their migration, please see Crane Spotting.



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