Sandhill Cranes: Sojourners from the North

Guest post by Elizabeth Blaker, Photos by Dyer Lytle

The distant wild trumpeting of cranes and geese on the wing raised the hair on the back of my neck from the sheer thrill of it. I had never seen nor heard such multitudes of geese, cranes, and ducks flying over until my first trip to Bosque del Apache National Wildlife Refuge near Socorro, New Mexico. From up the Rio Grande waves and waves of approaching birds were faint charcoal scribbles against the twilight sky. Closer and closer they came, slowly resolving into distinct V’s. The first arriving snow geese circled the flooded fields, splashing down into the water like seaplanes.  Ducks flew high with quick short wing-beats, while the longer wing-beats of the geese rowed the air. The first V’s of Sandhill Cranes sailed in, as light as thistledown, circling low, their ululations like a declaration of triumph. Barely skimming the water’s surface, they brought their legs forward and dropped out of the sky, landing with a light hop or two.

Around twenty-thousand Sandhill Cranes and a similar number of geese winter in the Middle Rio Grande Valley each year. The geese come from as far away as Canada, while the Sandhill Cranes breed in the northern states, Canada, and on up into Siberia. They are sojourners from the north, reminding me of distant summer prairies, lakes, and sloughs, and also of a time before history when birds filled the sky without number.

Sandhill crane take-off.

Sandhill Cranes are a particularly ancient species. A nine million year old fossil is nearly identical to the bones of modern Sandhills. These birds have a prehistoric look, too, long legged and winged, powerfully beaked, a blaze of crimson skin on their foreheads. When a Sandhill Crane is excited, the bright red skin engorges with blood and expands, extending to cover the crown of the head. Gray feathers tinged with rust drape their bodies, graceful plumes trailing. There are three subspecies of Sandhill Cranes distinguishable from each other by size: the Lesser Sandhill Cranes, Intermediate or Rocky Mountain Sandhills, and the Greater Sandhill Cranes. Genetic analysis shows that the Rocky Mountain and Greater Sandhills are more closely related to each other than to the Lesser Sandhill Cranes. The Lesser Sandhills migrate the furthest and have the largest wing-span to body-weight ratio. The added lift saves energy during long distance flights. All Sandhill Cranes are efficient flyers, migrating mostly by day to so they can use the rising sun-warmed air to carry them high into the sky – using a minimum of languid flapping, they slide down the edges of the thermals at a shallow angle, speeding along at 50 miles per hour as they gradually lose altitude until they come to the next thermal which carries them up. In this manner they can fly five hundred miles in a day.

Three sandhill cranes trumpet in unison.

They are no fools, these cranes. Instead of migrating in one go, they make the long journey in stages. The majority of Sandhill Cranes flying north from wintering grounds in Texas, New Mexico and Arizona stop along the Platte River in Nebraska, where they spend a few weeks resting and feeding on waste corn in nearby fields. When they have regained their energy, they fly on. Those making for Siberia stop over again in Alaska before the final push to their breeding grounds. We know this from a study in which researchers captured a small group of the cranes using rocket propelled nets fired from special gun-like devices (one brand is called the NET-ZOOKA). The scientists fitted each crane with a small transmitter that could be tracked by satellite as they flew their migration routes. Researchers continue to learn more about the migration patterns of these birds, and have made fairly detailed maps. As good as Sandhill Cranes are at long distance flights, it turns out there are groups of them living in Florida and Cuba that don’t bother to migrate at all – why should they when they are living the good life?

Sandhill Cranes disperse over large areas on their breeding grounds. They are territorial nesters, sometimes fighting each other over prime sites. Though they form strong pair bonds that can last many years, if a mate dies, the widow or widower crane will usually find a new mate. Once settled at the breeding grounds a crane couple will begin age old mating rituals. First they smear mud and rotting vegetation into their feathers. If the soil is rich in iron, their feathers retain a tinge of rust well into winter. Biologists posit that it aids in camouflaging the birds during their long vigil of nest sitting. After the feathers have been properly adorned with mud, the male throws his head back and utters a series of loud, vibrating honks. The female raises her head, but not as far, and replies with trumpet blasts of her own. They may perform several rounds of raucous duets. The duets strengthen the bonds between the pair and stimulates a flood of hormones in the female that prepares her ovaries for breeding. The blaring songs also proclaim their territory to other cranes. Though the duets are an important part of the mating ritual, Sandhill Cranes can be seen calling this way on their wintering grounds as well, and sometimes the fledglings join in. Researchers suspect unison calling at these times is likely to ward off aggression in crowds of other cranes.

A sandhill crane approaches a landing and puts its feet down in anticipation.

All kinds of cranes are known worldwide for their elaborate dances. Dancing is part of a complex of social behaviors and is not simply a mating ritual; it occurs in groups, between males, and so on. Dancing cranes bow and leap, they sprint with wings flapping, they hold stylish poses that impress onlookers, bird and human alike. But when a couple is finally ready to mate, one or both of them will lean forward as if to fly, heads raised, but instead hold this posture for a time. The male then circles behind the female. If she is receptive, she will lift her wings and allow him to mount. Afterwards, they face each other bill to bill and sedately bow.

Though the male may attempt to help her, the female ignores his offers of nest materials and builds a simple bowl of grasses and twigs on the ground. Over two days she will lay two spotted eggs.  These the couple will incubate, taking turns at nest-sitting and guarding for thirty days.  Finally the parent cranes hear the older chick peeping inside its egg, the shell cracks, and over many hours the chick frees itself with no help from them. The second chick hatches two days later. Sometimes the chicks fight with each other and the older may kill the younger, but if the parents manage to separate them, one chick will follow mom, and the other will follow dad. The parents teach the chicks how to find tasty roots, insects and other morsels.

Sandhill cranes flying against an orange New Mexico sunset.

Nesting and raising chicks is a race against time, especially for the Lesser Sandhill cranes breeding in the far north. They must mate and incubate the eggs early enough in the season that the chicks can fledge before they must begin their journey southward. If they wait too long, chicks will freeze or starve. It takes at least sixty days for a lesser Sandhill Crane chick to fledge.

As recently as the 1930’s, the Sandhill Cranes were nearly finished off by hunting and habitat destruction. Thanks to the unceasing efforts of a crew of dedicated amateur and professional ornithologists, refuges were established at breeding, migratory staging, and wintering grounds. Hunting was banned. Over many years the population of Sandhill Cranes rebounded.  Hunting is now allowed in several states, but not wantonly. The US Fish and Wildlife Service and state agencies carefully monitor crane populations and the numbers of birds killed. But I do wonder, who could stand at the edge of a marsh listening to the wild cries of birds on the wing, seeing these stately sojourners from the north riding the air currents down from the heavens, and not be moved?

This article originally appeared on dyerlytle.com/ravendreaming/