Scientists estimate that at least one-third of the entire North American population of sandhill cranes breeds in the boreal forest of Canada and Alaska.
Of all 15 crane species in the world, sandhill cranes are the most numerous and wide-ranging. In North America, there are several recognized subspecies including two non-migratory populations that are each restricted to Mississippi and Florida.
Scientists estimate that approximately 80 percent of all sandhill cranes in North America use a 75-mile stretch of Nebraska’s Platte River during spring migration. From March to April, more than 500,000 birds spend time in the area preparing for the long journey north to their breeding grounds in Canada and Alaska. During migration, the birds may fly as much as 400 miles in one day.
Sandhill cranes rely on open freshwater wetlands for most of their lifecycle. Degradation of these kinds of wetland habitats are among the most pressing threats to the survival of sandhill cranes.
Some evidence points to cranes as the oldest known bird species surviving on Earth. A crane fossil found in Nebraska, estimated to be about 10 million years old, is identical in structure to the modern sandhill crane.
Though cranes and herons share some similarities in appearance, they are actually only distantly related. In the wild, cranes can live an average of 10-20 years, but herons usually survive for little more than five or six years. Herons also lay more eggs than cranes, typically four to seven eggs while cranes will generally lay only two. It can be difficult to tell the difference between herons and cranes in flight. One of the easiest ways to distinguish the birds is to remember that herons fly with their necks curved and cranes fly with their necks straight.March 07, 2011