Organizing for Endangered and Threatened Species Habitat Draft

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? ? ? ? ? The whooping crane population has rebounded a bit because of habitat acquisition, ? federal protection, and intense management of breeding and wintering areas. By 1987, 136 birds ? were in the wild, and populations fluctuated around that number until 1995 when a peak • wintering population of 158 birds was recorded (U.S. Fish & Wildlife Service 1997). In 1998 about 200 whooping cranes made up the North American mid-continent flock, out of 400 ? worldwide. The Big Bend stretch of the Platte river in central Nebraska has presented an extremely favorable combination of habitat types, hosting bald eagles, peregrine falcons, over 10 million ducks and geese, eskimo curlew, and over a half million sandhill cranes along with their rare cousin the few whooping cranes. The area between Lexington and Chapman is witness to over eighty percent of the world's sandhill cranes spending 4 to 6 weeks in spring, resting and feeding before continuing the migration north Over 300 species of migrating birds use the Platte seasonally, of which 125 nest along its banks (Grooms 1991: 20). The entire natural flock of whooping cranes currently migrates through Nebraska between the wintering grounds at Aransas National Wildlife Refuge and their nesting grounds in Wood Buffalo National Park, Canada. This central Nebraska patch has been called the waist of a habitat hourglass-millions of birds depending on the few resources available. Weeks later they spread out over wide ranging sparsely populated breeding grounds. At no other time of the year are cranes so concentrated as on the Platte (Grooms 1991: 116). In early spring along the Gulf Coast, Figure 3 Crane Migration Flyway Southwest and northern Mexico, cranes begin calling and gathering together for the annual migration north (Figure 3). Both sandhill and whooping cranes fly in daylight, relying on thermal updrafts to improve efficiency and minimize energy expenditures. Riding an updraft and then gliding northward, they steadily lose altitude until the next thermal lifts them and they repeat the process. Often flying a mile above the earth, they can soar to 20,000 feet above sea level. They arrive at a staging area along the Platte river by late February and early March, descending from cold wintry skies into sandhill country, with rolling hills and marshes, oxbows and shallow lakes, close to brown harvested cornfields. Wide expanses of shallow water offer protection from predators that have to make a long splashing attacks. Stopping along the Platte to replenish reserves and add fat, cranes depart by mid-April for the last push, following the spring thaw north to summer breeding grounds. Arriving in the sub- and arctic region, especially around the Great Slave Lake of the Canadian Northwest Territory they build a platform nest of rushes, and raise one or two young each year. Whooping cranes mate for life, and vigorously defend their territories in both summer and wintering grounds 10