Sandhill Cranes

For the past week, we have been hearing warbling sounds from high overhead as sandhill cranes return to their spring breeding areas from their winter stay in Mexico and the southern U.S.  Even though their large size makes it possible to see these birds for long distances, they fly at such high altitudes that their size looks deceptively tiny, making them hard to find in bright daylight skies.  Flying in a ‘V’-shaped pattern, flocks from a dozen to several hundred noisy birds pass by repeatedly during the day. 

Sandhill cranes, Antigone canadensis, are classified into five subspecies.  Lesser sandhill cranes, A.c. canadensis, and greater sandhill cranes, A.c. tabida, both overwinter in Florida and Mexico.  In spring, they migrate north to breeding grounds in the northern U.S. and across Canada into the Arctic, Alaska and northeast Siberia.  There are two separate flyways, one from Florida bearing slightly northwest and passing through Indiana and Illinois.  The second is from Mexico heading due north through Texas, Nebraska, and Colorado.  Three quarters of all the cranes will pass through the Sand Hills region of Nebraska from which their name is derived.  This flock, crossing the Platte River area in spring, is comprised of 250,000 to 500,000 birds.  There are three small populations of non-migratory birds named for their respective locations including the Florida sandhill, A.c. pratensis; the Cuban sandhill A.c. nesiotes, and the Mississippi sandhill, A.c. pulla.

Sandhills are large birds, standing between 3’6″ and 5′ tall.  Their broad wingspans of up to six feet provide enough power to lift their considerable weight, for a bird, of six to fourteen pounds.  They have a small head, long straight bill, a long neck, and a short tail covered by drooping feathers called a “bustle”.  Cranes are slate gray with pale cheeks and black legs.  Adults display a bright red crown and some rusty tones in their backs from mud used in preening.

Birds fly during the day when the sun is up and air currents are strongest.  The birds will use thermals, a column of air that is heated by the sun and rises upwards, to carry them aloft.  As cranes ascend, they are searching for air currents blowing in the direction they want to fly.  Typically, they will fly between 4,000 and 5,000 feet high, but may ride a thermal all the way up 12,000 feet.  Cranes are able to cover 150 to 400 miles each day at speeds of 15 to 50 miles per hour.

Upon reaching their summer breeding grounds, both sexes will engage in courtship displays that includes a dance involving outstretched wings and head pumping, bowing and leaping into the air.  Males and females will call in unison as part of their bonding.  They mate for life, only taking another partner if one dies.  A normal life span is a little over twenty years; the oldest recorded bird was 36 years 7 months old.  Females may begin breeding as early as age two, but most are seven years old and up.  They will lay 1-2 eggs, but normally only one survives.  The juvenile, called a ‘colt’, will remain with the parents for 10-12 months, until leaving for their own life the spring following their birth.

Fossils found in Nebraska date from the Miocene period about ten million years ago.  The bone structure of the fossils is the same as what is found in today’s birds, making the sandhill crane one of the oldest species of birds.  In the late 19th century, they were hunted for the wild meat market until they were considered extirpated east of the Mississippi River.  The Migratory Bird Treaty Act of 1918, passed with support of several early conservationists, is considered to be the critical step that saved the sandhill crane.  Current populations are doing well, but growing slowly since only one chick is born annually.  Conservation of all five species, especially the non-migratory birds, is tied to the preservation of wetlands for migratory staging and breeding.

Now is the time of year to get outside in late morning through the afternoon and listen for their warble, then see these great flocks heading northward overhead.  To learn more, take a look at the International Crane Foundation website at: https://www.savingcranes.org/