On the wild side—November, 2012
by Tina Mitchell
North America has only 2 species of cranes: the desperately endangered Whooping Crane and the more common Sandhill Crane, which we see and (more often) hear migrating through our area. Standing 3 – 4 feet tall with a wingspan of 6 – 7 feet, the Sandhill Crane can be distinguished from most other long-necked heron-like birds by its clunky, bottom-heavy body and a droopy tail that resembles an old-fashioned feather duster. If you ever see one of these predominantly gray giants up close, you’ll also spot a red crown and a surprisingly small head that wields a large, dangerous-looking, dagger-like bill. Flying high overhead, a crane’s neck stretches out straight (unlike a similar-looking Great Blue Heron, which flies with a folded neck) and its legs trail behind. Males and females look similar although males tend to be a bit larger. In reality, though, most of us will hear cranes long before we can see them—if we ever see them. An adult’s call is loud, resonant, and unforgettable. In migration, a flock sounds like a symphony of giant, stuttering, creaking hinges. A crane’s windpipe coils into its chest, allowing the sounds to resonate even more. But honestly, words will never be able to adequately capture this sound. Click here to listen to this amazing sound. If you plug in headphones and turn the volume way up, you’ll come close to the actual experience.
Most people will experience the magic of Sandhill Cranes primarily during spring and fall migrations, although a few pairs breed in northwest Colorado. An important gathering or staging area for Sandhills in both spring and fall migration is the San Luis Valley—the Monte Vista National Wildlife Refuge, to be precise. On the flight path between western breeding grounds and wintering sites in New Mexico and Mexico, this area hosts nearly every member of the cranes that breed in Idaho, western Montana, Wyoming, Colorado, and Utah. Every year, Monte Vista hosts a Crane Festival in early March honoring the return of the Sandhills. If you ever get a chance to go, you will never forget it! (If you can’t wait until March and have a rambling itch, check out the 25th Festival of the Cranes at the Bosque del Apache National Wildlife Refuge in Socorro, NM this month—November 13 – 18!)
Sandhill Cranes mature slowly, delaying breeding until 2 to 7 years of age, depending on the subspecies. They are strongly monogamous and both parents care for their young. They usually nest near wetlands (e.g., marshes, bogs), in nearby open grassland or in areas surrounded by woodlands. A clutch usually contains 2 eggs, which both parents help to incubate for 29 – 32 days. The precocial young leave the nest within a day of hatching, following the parents to appropriate feeding areas. Despite hatching 2 chicks, usually only 1 survives—perhaps due to nestling-on-nestling harassment. Both parents feed the young at first, but the youngster soon feeds itself. First flight occurs between 65 and 75 days after hatching. The family remains together for 9 or 10 months, allowing the young crane to learn the migration path from their parents.
A Sandhill’s diet varies widely, depending on the location and the season. Foods range from insects, aquatic plants, rodents, a variety of amphibians and reptiles, and even berries and seeds. Preparing for and during migration, Sandhills can often be found in fields of cultivated grains when those are available. (Areas around staging and wintering grounds such as Monte Vista and Bosque often abut corn fields; typically, managers leave some grains to provide important bulking-up nourishment.)
The Sandhill Crane’s scientific name is Grus canadensis. Grus comes from the Latin word for a crane; the species name canadensis refers to its breeding grounds in Canada. The term “crane” derives from the Anglo-Saxon word cran, which refers also this bird. Finally, “sandhill” refers to the small sandhills which are a preferred site for their courtship display—an impressive dance of leaps, bows, and hops.
The population of all subspecies of Sandhill Crane is estimated to be somewhere around 650,000. The subspecies in our area—the Greater Sandhill Crane—has made a significant comeback in the past 70 years. In 1940, the population was estimated to be only 1,000; today, estimates hover around 100,000. The Rocky Mountain Population that passes through our area numbers about 20,000. Colorado Parks and Wildlife (formerly the Division of Wildlife) considers this population to be a “species of concern” due to habitat loss and other disturbance by humans. As a result, hunting seasons for cranes in our area have been closed. However, the eastern plains of Colorado mark the western edge of the migration corridor for a different population of Sandhill Cranes; a hunting season exists for all subspecies of cranes in that area and in most other states in their range.
Sandhill Cranes live long lives, as far as wild birds go—often more than 20 years. They also rank among the oldest living birds on the planet, with fossil records dating back 9 million years. This vast evolutionary record prompted Aldo Leopold to write in A Sand County almanac (1949):
His tribe, we now know, stems out of the remote Eocene [period]. The other members of the fauna in which he originated are long since entombed within the hills. When we hear his call we hear no mere bird. We hear the trumpet in the orchestra of evolution.
When Sandhill Cranes pass noisily high overhead, you indeed hear trumpets and echoes from millennia long past—living fossils traveling an ages-old path twice a year since the dawn of time.
Click here to learn more about Sandhill Cranes.