On a Lost Path
The Whooping Crane (Grus americana), a close relative to
the smaller Sandhill Crane (Grus canadensis), stands nearly 5 feet tall,
with a long, sinuous neck and long legs. Its snow-white feathers are accented
by jet black wing tips. The head is marked red and black, and the wingspan
is about 7-1/2 feet.
A Rocky History
Whooping Cranes symbolize the current struggle to maintain the vanishing
creatures of our world. At the turn of the 20th century, the Whooping Crane’s
environment changed and their numbers declined. The wetlands they depended
on for food and nest sites were drained to accommodate development. Hunters,
too, took their toll, sometimes mistaking Whoopers for other birds. By
1941 there were only 15 birds left, members of a flock that wintered on
the salt marshes and tidal flats of the south Texas coast on the Aransas
National Wildlife Refuge.
Back from the Brink of Extinction
For years, no one knew where this endangered species nested and raised their
young. Then in 1954, a pilot flying over the remote Wood Buffalo National
Park in the Northwest Territories of Canada spotted a pair of Whooping
Cranes and a possible chick. The discovery enabled scientists in the United
States and Canada to study the birds and find ways to save them from extinction.
State and Federal officials from both countries, along with private conservation
groups, began tracking the spring and fall migration and alerting the public
to the Whooping Crane’s plight. Through concerted efforts, these agencies
and conservation groups have worked to increase the number of Whoopers to
399 (2002).
The Cross-Fostering Experiment
In 1975, there was only one self-sustaining (wild) population of Whooping
Cranes in the world. Fearing that this flock might be lost to disease or
a late fall hurricane, recovery objectives were developed in the Whooping
Crane Recovery Plan calling for the establishment of two additional self-sustaining
wild populations.
As a long-lived species, cranes learn migration routes and other behaviors from their parents rather than know them by instinct (like short-lived songbirds). So biologists looked for other wild cranes which would be appropriate surrogate parents (called cross-fostering). The Rocky Mountain Population of Sandhill Cranes proved to be an ideal source of potential parents for Whooping Crane chicks.
The Rocky Mountain Population (RMP) of Greater Sandhill Cranes numbers about 25,000 birds (1999). These cranes migrate twice a year between their breeding grounds on/near Gray’s Lake National Wildlife Refuge (NWR), Idaho and their winter areas on/near the Bosque del Apache NWR, New Mexico. During the spring and fall migration, the flock stops in the SLV for several weeks to rest and feed.
A cross-fostering experiment was initiated in1975 by the U.S. Fish and Wildlife Service (USFWS) and the Canadian Wildlife Service (CWS) to establish a second self-sustaining flock. Whooping Crane eggs from both wild and captive populations were transferred to Sandhill Crane nests at Gray’s Lake NWR, Idaho. While Whooping Cranes lay 2 eggs, only one chick typically survives, therefore removing one egg from a nest did not affect productivity and likely enhanced the survival of the remaining chick. The Sandhill Cranes hatched and raised the Whooping Cranes as their own. In all, 289 Whooping Crane eggs were transplanted in Sandhill Crane nests, of which 85 chicks learned to migrate.
