CELPIP Reading Part 3 Practice Test: Whooping Cranes Back From The Brink

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Standing about one and a half metres tall, the whooping crane is the tallest bird in North America. Adults are bright white, with black wingtips that can be seen only when the wings are spread and a patch of red skin on the crown. The species takes its name from its loud, trumpeting call, which can be heard from a great distance across open marshland. The cranes were once found across much of the continent’s interior, but as settlers drained wetlands to create farmland and hunters shot the birds for food and feathers, their numbers collapsed. By the early 1940s, fewer than two dozen whooping cranes survived in the wild, and many experts expected the species to disappear.

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One of the greatest obstacles to saving the birds was that no one knew where they raised their young. Each autumn the remaining flock arrived on the Gulf Coast of Texas, but its summer home remained a mystery for years. The answer came unexpectedly in 1954, when people working on a forest fire in a remote part of Wood Buffalo National Park spotted cranes from the air. The park, which straddles the border between Alberta and the Northwest Territories, is still the only natural nesting ground of the original wild flock. Every spring, the birds fly roughly 4,000 kilometres north to its isolated wetlands, returning to Texas in the fall.

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Recovery has depended on close cooperation between Canada and the United States. Both countries gave the cranes legal protection and worked to safeguard important habitat. Biologists also made use of a simple observation: although a pair usually lays two eggs, it rarely raises more than one chick. Beginning in the late 1960s, researchers removed one egg from some nests in Wood Buffalo and hatched the chicks in captivity, building up breeding flocks without reducing the number of young produced in the wild. Captive-bred birds were later released in an effort to establish new flocks elsewhere. In one well-known project, young cranes learned a migration route by following a small, slow-flying aircraft.

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Today, the wild flock that travels between Wood Buffalo and Texas numbers more than 500 birds, making the whooping crane one of North America’s best-known conservation success stories. Experts warn, however, that the job is not finished. Whooping cranes do not breed until they are several years old and raise few young, so the population can only grow slowly. Collisions with power lines kill birds during migration, and because almost all of the only self-sustaining wild flock depends on the same two areas, a single disaster, such as a major storm or an oil spill on the Texas coast, could undo decades of progress. For now, the species remains listed as endangered in both countries.