(Chelsea Update would like to thank Tom Hodgson and the Waterloo Natural History Association.)
Sandhill cranes are once again being spotted in the Chelsea area. After spending the coldest winter months in points further south from Tennessee to Florida, they are returning to claim their nesting territories once again.
The spring migration is rather low-key, as there are no large concentrations of birds as in the fall. Instead, breeding pairs go straight to their nesting territories. Those that bred successfully in the previous season will be accompanied by their latest offspring.
Once nesting begins in earnest, however, the adult birds will not tolerate these youngsters on their breeding territories. They will be driven off to spend the next three years in small groups of sub-adult, bachelor birds before selecting mates and territories of their own.
Though the scattered pairs observed in spring may not be as impressive as the large numbers seen in the fall, they make up for this with their booming territorial unison calls that warn other breeding pairs to stay away. Calls that are so loud they can be heard from a mile or more.
Cranes nest in area marshes, some as small as a few acres. Their nests, built from marsh vegetation, resemble soggy hay stacks and are about three feet in diameter. By late March most nests will contain two eggs, the first laid and incubated a day or two before the second.
Incubation takes about thirty days. The first egg hatches a day or two before the second. The first chick (called a colt) has a definite advantage over the second, and is the only one to survive during most years. Those who are growing tired of winter can take heart. With the sandhill cranes returning, spring weather cannot be far behind.