As the rays of the rising sun penetrate the morning mist, the birds take shape, and a fantastic scene unrolls in front of us. In the shallow waters of the river, about 50,000 cranes are standing shoulder by shoulder. Their trumpeting now intensifies, and the birds begin to shift restlessly, a few of them performing their graceful dance. Then, with an incredible crescendo of trumpeting, the birds take flight, flock after flock heading for the surrounding maize fields, where they eat waste kernels, left over from the harvest. Farmers consider the cranes beneficial, as sprouted maize kernels from the previous year are regarded as a weed.
Every year, during their spring migration in March and April, huge flocks of sandhill cranes roost here for a few weeks before continuing to their breeding grounds in swamps and lakes further north. The cranes used to roost in many prairie rivers, but today most of these rivers are regulated by dams, causing most of the sandbars, on which the birds roost, to be either submerged or covered in dense vegetation, such as willows, because the sandbars are no longer inundated by spring flooding. Along the Platte River, much work is done to clear these thickets, causing about 80% of the world population of sandhill cranes to roost here.
Northern populations, including the Siberian breeding birds, spend the winter in south-western U.S. and Mexico, while southern birds are resident. The populations in Mississippi and on Cuba are very small and threatened with extinction.
In Nebraska, researchers have found 10-million-year-old skeletal parts of a crane, very similar to the ones of the modern sandhill crane, but probably a different species. However, 2.5-million-year-old subfossils of sandhill cranes have been found, still making it one of the oldest living bird species today.
Recently, the sandhill crane has expanded its range far west into Siberia, and the Russian population today exceeds 10,000 birds. Traditionally, Russian hunters do not shoot the cranes, but in later years the sandhill crane has become so numerous that some hunting of the species takes place. As the cranes are omnivorous, they eat whatever they can find: roots, insects, mice, and eggs and young of numerous species of birds.
In later years, several Siberian wader species have declined drastically, mainly due to habitat destruction on their flyways between breeding and wintering grounds. In China, Korea, and Vietnam, huge areas of coastal shallow waters have been converted into shrimp farms, salt pans, or fields – areas which migrating waders are dependent on for fattening up, before continuing to their breeding grounds.
Many waders are now in a poor condition, when they arrive in Arctic Siberia, which means that they produce fewer young – or simply skip breeding. Thus, production of chicks has plummeted in many species, and one species, the spoon-billed sandpiper (Eurynorhynchus pygmeus), is critically endangered, with less than a hundred breeding pairs.
Under these circumstances, marauding sandhill cranes do make a difference, and the beautiful birds have become a threat to Siberian breeding waders.