Elegant Departure: Sandhill Cranes bid farewell
November 7, 2009, was an unseasonably balmy late fall day, about 65 degrees, sunny, with a southerly breeze. I was raking leaves in northern Washington County, when the distinctive bugling call of sandhill cranes came drifting through the air. I looked up to see a flock of about 30 birds overhead, soaring and circling as they rode a thermal to gain altitude, then gracefully gliding off in a southeasterly direction. Stretching out to about 5 feet, with a wingspan of five to six feet, they were quite a sight against the clear blue sky. My guess is they were headed for the St Croix River, leading them to the Mississippi River and points south. Several more flocks followed throughout the afternoon, calling farewells as they went.
While there is just one species of sandhill crane in North American, it is divided into six subspecies, of which three are migratory and three are not. Each subspecies is further broken into multiple populations. The Greater Sandhill Crane is the subspecies found in Minnesota, with a breeding range that extends from the Great Lakes to the Pacific Ocean in the northern United States and southern Canada. This subspecies is made up of five populations. The birds I saw were likely part of the Eastern population, which breeds in Michigan, Wisconsin, southern Ontario, southeastern Minnesota, northern Illinois, and northern Iowa. Most of this population overwinters in southern Georgia and central Florida, with some from the western part of the population overwintering along the Texas Gulf Coast. The major spring and fall stopover area is Jasper-Pulaski Fish and Wildlife Area in Northwest Indiana.
The Birds of North America Online provides an amazing amount of detail on flight patterns and habits. Migration flights usually begin 1.5 to 5 hours after sunrise, and stops 0.25 to 2 hours before sunset, occasionally continuing after dark, for a total flight time of 1 to 10 hours. Average flight distance is 250 km (155 miles) at speeds of 23 to 83 km/hr (14 to 51 mi/hr). The US Fish and Wildlife Service has recorded flights up to 342 miles per day from radio-tagged birds. The cranes use three different flight methods: flapping (unidirectional powered flight), spiraling (soaring upward on thermals in a spiral), and gliding (unidirectional with altitude loss). They migrate in a V formation at altitudes of up to 3,600 meters; (2.2 miles), but 75% of flights are between 150 meters and 760 meters (492 ft to 2,493 ft).
The details are interesting, but the best part is the wonderment of simply observing of these elegant creatures and hearing their calls. Ill be eagerly listening for their return to my neighborhood next spring, where they typically arrive around March 15.