ALBUQUERQUE — For more than a decade scientists have been trying to build up a flock of whooping cranes that commute between Idaho and New Mexico by stealing eggs from a nesting ground in Canada.
It's a tedious process with a lot of setbacks. At last count only 10 of the majestic birds were wintering at New Mexico's 57,000-acre Bosque del Apache National Wildlife Refuge, with 10 to 11 spotted elsewhere in the middle Rio Grande Valley.
Not to worry. A second flock of 111 whoopers appears to be thriving. That flock migrated 2,500 miles from its summer nesting grounds at Wood Buffalo National Park in Canada's Northwest Territory to the Aransas National Wildlife Refuge on the Gulf Coast of Texas.
"This is the first time they've exceeded 100 in a winter since early this century or late last century," said James Lewis, whooping crane coordinator for the U.S. Fish and Wildlife Service.
"In the last three years, we have had excellent production in Canada due to very good water and food conditions. We have had a substantial number of nesting pairs, 28 or 29, in each of the last three years."
Of 21 young birds that reached flight age in Canada last year, 20 arrived for the winter at Aransas and another was found with a group of sandhill cranes in western Oklahoma.
"It's real unusual to have this kind of survival rate among the Canadian cranes," Lewis said.
The endangered whoopers, great white birds that stand about 5 feet tall with a wingspan of 7 1/2 feet, had a problem with a flotilla of noisy neighbors last winter at the New Mexico refuge. There just was not enough living space and food for them and thousands of geese.
But some fireworks and a noisy airboat took care of the problem this year.
56,800 Geese at Site
Robert Edens, outdoor recreation planner at the Bosque del Apache, said there were as many as 56,800 geese at the refuge last winter, while the area can handle only about 20,000 to 25,000.
"Food competition was a concern there because of the large numbers of birds," Lewis said.
"We had three whoopers that got avian tuberculosis last spring. A possible source of the disease was the concentrations of other waterfowl at the Bosque."
Edens said that when about 37,500 geese alighted at the refuge in November, "We had a 14-day marsh hunt. We used an airboat on the Rio Grande. People in the field used pyrotechnics--shell crackers and whistle bombs. We tried not to get anywhere near the whoopers or near the sandhill cranes."
Apparently most of the geese fled south, with about 13,000 remaining at the refuge, he said.
Whooping cranes have rebounded from a low of 15 in the wild in 1941 to 177 today in two wild flocks and a captive flock.
Some of Flock in Mexico
While 20 or 21 whoopers were counted in New Mexico's middle Rio Grande Valley in early February, biologists suspect others from the Idaho flock of 26 may be in northern Mexico.
"They usually show up here about the first part of November and they can stay through around mid-March," Edens said.
The New Mexico whoopers are part of an experimental flock from the Grays Lake National Wildlife Refuge in southeastern Idaho.
Since 1975, scientists have been stealing whooping crane eggs from the great birds' only nesting site, in Canada, and putting them in sandhill crane nests in the Idaho refuges.
Since cranes lay two eggs but only raise one chick, the existing crane flock was not threatened.
Raised by Sandhill Cranes
The adopted whoopers are raised by their sandhill parents and the families travel 750 miles to their wintering grounds in New Mexico.
But the flock did not have a very good breeding season last year, Lewis said. Of 21 whooper eggs transferred to Grays Lake, six were found to be bad.
"Of the 15 remaining, two were taken by predators at the nest and two others failed to hatch," he said. "Eleven hatched, but they had a drought at Grays Lake and a lot of problems with predators. Two chicks, as far as we know, are still alive."
Tom Smylie, spokesman for the Fish and Wildlife Service, said there is concern that the flock has not increased.
'Is No Courtship'
"For the number of birds we have introduced, the flock should be growing, but there is no courtship," he said.
A captive flock of 38 whoopers at the Patuxent Wildlife Research Center at Laurel, Md., also had a disappointing breeding season last year, he said. New breeding pens were built, but in the spring breeding season the birds didn't lay any eggs.
"They did raise two chicks at Patuxent, but they were eggs from Canada and weren't laid at the site," Smylie said. "Those two chicks are still OK."
There are two other captive whoopers--one at the International Crane Foundation at Baraboo, Wis., and another at a zoo in San Antonio, Tex.
"We're disappointed about the captive flock and we hope that it will jump back this spring," Lewis said. "We have five proven breeding pairs. We have 10 other breeding pairs forming, and we hope they start breeding in the next few years."