Every year in the month of March, one of the world's greatest wildlife migrations stops in central Nebraska. For a short time, sandhill cranes fill the state’s wide, flat fields. The land provides these long-legged, playful birds with the perfect place to rest and eat. Last year, a record 1 million sandhill cranes stopped in the area during their northward migration. That is about 85 percent of the world’s sandhill crane population. In recent years, more and more people have discovered the migration. Visitors crowd into river blinds, special structures that help keep the birdwatchers hidden. They look through their cameras or binoculars in wonder. Only one other migration on Earth is as concentrated and wondrous, local scientists say. That is the wildebeest migration in Africa.