That was 1992, fall. We were driving across New Mexico and decided to stop at the Bosque del Apache National Wildlife Refuge south of Socorro. We had read that Bosque was the wintering ground of thousands of sandhill cranes and snow geese, of ducks and grebes and many other birds. As if that wasn’t enough inducement for bird watchers like us to stop, at that time Bosque had whooping cranes, birds what were part of an effort to establish a second migratory flock of these great birds, the tallest in North America.
To establish this flock eggs had been taken from the nests of whooping cranes at Wood Buffalo National Park in Canada’s Northwest territories and put in the nests of sandhill cranes at Grays Lake National Wildlife Refuge in southeast Idaho. Taking eggs from successfully nesting whooping cranes to put in the nests of sandhill cranes doesn’t sound like a good idea at first. But biologists studying the whoopers had found that they laid two eggs in a nest but rarely raised more than one chick. Taking one egg from a pair, they reasoned, would make no difference in their overall reproduction.
Once the eggs had been collected from whooper nests, transported and put in sandhill nests it was up to the sandhills. They had to hatch the eggs, raise the fledglings and teach them to survive, to migrate and eventually to mate and nest and raise young of their own.
From 1975 to 1989 whooping cranes’ eggs from Wood Buffalo National Park in Canada were put in sandhill crane nests at Grays Lake National Wildlife Refuge, Idaho. The sandhill cranes did their part, hatching the eggs, raising the young and leading them south to winter at the Bosque del Apache Refuge in New Mexico. And there, in 1992, we saw a whooping crane flying with three sandhill cranes when we were stopped for gas at Socorro, a few miles north of Bosque del Apache. Visiting the refuge soon after that we saw two more whooping cranes. We visited Bosque in the fall again the next year, and again we saw whooping cranes.
But you could say the sandhill cranes did their job too well. They taught the whoopers to mate with birds like their surrogate parents, gray birds, sandhill cranes, not cranes of their own breed. So, though the whooping cranes lived for several years they failed to reproduce themselves.
In a last effort to establish a flock of whooping cranes that were hatched at Grays Lake and migrated to Bosque del Apache, young whoopers, hatched by sand-hill cranes, were taken and taught to follow ultralite aircraft, then led by ultralites from Grays Lake to Bosque. It was thought, I presume, that if they traveled south only with other cranes of their kind, other whoopers, in the spring they would mate with others of their kind.
Again we visited Bosque del Apache in the fall. We were present that year when the planes with their following whooping cranes arrived. Those cranes, too however, failed to mate with other whoopers and reproduce their kind.
Last month we visited Grays Lake National Refuge, once a place of sand-hill and whooping cranes. But there are no whooping cranes there now nor are there any at Bosque del Apache.