Nature’s World:  SANDHILLS IN SPRING

by Susan Tweit

  One recent afternoon, a friend phoned in a state of great excitement. He had been walking his dog on the mesa just outside town, he said, when he’d heard a distant, trumpeting “Krraugh! Krraugh!” call.

At first he couldn’t figure out where the sound came from, but then he looked up in the sky and saw thousands of huge birds circling high overhead and calling at regular intervals. “What are they?” he asked me.

It took me a minute, and then I remembered. It’s spring: sandhill crane migration time.

Sandhill cranes are unforgettable birds, whether seen on the ground or high in the air. One of North America’s largest bird species, they stand more than four feet tall, striding across the ground on stilt-like legs, heads held high on long, graceful necks.

In the air, sandhill cranes ride on enormous wings stretching as much as 7.5 feet from tip to tip. Even cranes’ windpipes are outsized, nearly five feet long. Amplified by that pipe, their sonorous “Krraugh! Krraugh!” calls can be heard for several miles.

Sandhills and their larger cousins, endangered whooping cranes, are easily told apart in adult plumage: whoopers are bright white with distinct black wingtips; sandhills are soft gray, often with a rusty tinge imparted by iron in the soils where they feed. Both species sport scarlet caps.

In western North America, sandhill cranes nest in freshwater marshes and wet meadows from the Rocky Mountains to as far north as the Arctic Circle. These sandhills head south for the winter, stopping at marshes in New Mexico, Arizona, and northern Mexico.

On route between wintering areas and nesting grounds, sandhills pass through central Colorado. Each March, some 17,000 of these birds arrive in the San Luis Valley to rest and tank up for the long commute farther north. (Alamosa holds a crane festival in March to celebrate their return.)

At night, the cranes gather en masse in the marshes of the wildlife refuges; by day, they fly out to feed in farm fields and wet meadows.

Sandhill cranes look like graceful oil pumps as they probe deep into the soil with their spear-like beaks, hunting insect larvae and the tubers and roots of aquatic plants, then draw up again, then dip down to probe again.

They also spear a wide variety of small animals, including rodents, snails, frogs, lizards, snakes, and nesting birds; and pick up the seeds of cultivated grains and wild grasses.

As the days grow warmer, the sandhills become restless. They take flight at the slightest disturbance, pushing into the air with their long legs and lifting off on wide wings, then circling and setting down again.

And they dance. Sandhill and whooping cranes both court their mates with stylized moves like avian ballet. The birds dance all year round, but increase their activity in spring.

A single crane will suddenly leap eight feet in the air with its wings stretched wide, land and bow on bent legs, then leap upwards again, wings outstretched. Or a pair will cross their long bills, then leap together with wings partly folded, trumpeting, stretching their necks straight towards the sky.

Sometime between late March and early May, depending on the weather, the sandhills leave the San Luis Valley and fly north on the last stage of their spring migration, headed for nesting areas. Strong fliers, these birds may cover several hundred miles in 24 hours.

Flocks of dozens to thousands of cranes lift off and circle upwards, soaring on rising currents of warm air to altitudes as high as 13,000 feet where they catch favorable wind currents and glide over mountain passes. They fly so high that often only their echoing calls reveal their passage.

That’s the sound our friend heard, walking his dog on a warm Saturday morning. And when he looked overhead, he saw thousands of cranes circling high in the sky, riding a thermal on their way north.

It’s comforting to me to know that no matter the chaos in the world, when spring arrives, sandhill cranes still pass overhead, headed north as their kind have for millions of years, on their way to lay eggs and raise new generations of young.

Spring comes, cranes migrate—life continues.

   © 2003 Susan J. Tweit