By Dianne Zuckerman
MONTE VISTA – A late afternoon white out is scarcely the ideal way to catch sight of the celebrated sandhill cranes that migrate every spring and fall through this small farming community in southern Colorado.
But shortly after embarking upon the self-guiding auto loop that meanders through a segment of Monte Vista National Wildlife Refuge, I’m surrounded by a sudden deluge of snowflakes. On one side of the road are patches of half-frozen ponds. On the other, frosted fields stretch to the horizon. As flakes whirl down like the Furies, I’m momentarily suspended in a white-gray world, my sense of direction scrambled, wondering if I’ll find my way back before nightfall.
Then the flakes stop falling as quickly as they began. I scan the sky and grassy expanses for a glimpse of the long-legged, russet-gray birds that stand almost 4 feet tall and have distinctive red crowns. Overhead, a trio of Canada geese are caught in an aerial obstacle course, wings straining against a strong wind. Down a nearby slope, a handful of hardy cinnamon teals skirt the ice-encrusted water. But so far, no cranes.
My first sighting of the elegant birds comes unexpectedly, as the final leg of the auto tour edges alongside wide meadows backed by bare-branched cottonwoods. Shivering from a chilly gust and wiping watery eyes, I suddenly comprehend that the smoke-colored blurs fading into darkening fields are cranes. Thousands of them. Seen through binoculars, they scratch the soil, enjoying their final bites of grain before flying to the interior sections of the 14,189-acre refuge to roost overnight in frigid, shallow ponds.
Watching the mass of sandhills that peck, strut and preen, I spy a curved white shape at the edge of the flock. A patch of snow? With growing excitement, I focus my binoculars on a breathtaking white form, one of the two whooping cranes that travel with the Rocky Mountain population of sandhills. As night swoops into the San Luis Valley, my first day of crane-spotting shifts from frustrating to memorable, a fitting introduction to the wonder of avian migration.
Monte Vista National Wildlife Refuge was created in 1953. But the cranes – whose huge, three-toed feet first trod the world’s wetlands at least 40 million years ago – have probably been migrating through Colorado for centuries.
Sandhills Return Twice Each Year
“It’s like an hourglass,” says Ron Garcia, deputy manager at Monte Vista and Alamosa National Wildlife Refuges. “Their nesting ground covers several states. Their wintering ground is fairly large as well. But they all bottleneck through the San Luis Valley during the fall and the spring.”
The Rocky Mountain population of sandhill cranes consists primarily of greater sandhills, with a scattering of lesser sandhills and Canadian sandhills. In spring, the birds usually arrive in mid-February and remain through the end of March. From April to August, the flock nests in the Greater Yellowstone area – Idaho, Montana and Wyoming – with the largest concentration centering on Grays Lake National Wildlife Refuge, a remote, marshy plateau near Pocatello, Idaho. The cranes trumpet back through Colorado from early September through November en route to wintering at Bosque del Apache National Wildlife Refuge in New Mexico.
What turned placid Monte Vista, population about 4,300, into the cranes’ major stopover point? “The attraction is the small grains, the wheat and barley,” Garcia says. But fields of waste grain – the leavings that remain after harvesting aren’t the only lure. “You have to have a combination of things,” he explains. The ideal mix is sufficient grain and water – the Rio Grande River winds through the Valley – and close proximity to roost sites such as ponds that dot the refuge. The absence of adjacent grain fields is why the Alamosa refuge, only about 20 miles away, doesn’t attract the cranes.
Cranes Losing Homelands
Sandhills traditionally protect themselves from coyotes and other predators by overnighting in low water, such as the ponds at the Monte Vista refuge. But predation isn’t the major threat during migration, Garcia notes. “Most of their mortality comes from collisions (with) power lines.”
The greatest danger of all is disappearing wetlands due to development, which in turn affects the cranes’ total population. The survey count is done in the fall, after breeding season, so this year’s numbers are not yet known. But for the past few years, the Rocky Mountain population of cranes has ranged between 18,000 and 22,000, which seems to be the maximum number of birds that can be supported by existing habitat. “Above that, it becomes stressful,” Garcia says. “So the goal is actually to keep them in that range.”
Natural mortality and decreased breeding linked to cycles of drought play a role in this. So does hunting. While greater sandhills are a protected species in Colorado, “Some of the states around us do hunt them. That’s why they do the production surveys, to let the states know how much of if they can hunt them at all. When the numbers are up, hunting’s allowed.”
While the concept makes sense when discussed in the abstract, it’s difficult to envision someone shooting down such beautiful creatures while watching the regal cranes streak off at sunrise the next day. Bodies straight as arrows, their wings span 5 feet and flap like smoothly synchronized fans. As clusters of birds head out for breakfast, the resultant percussive rustle is accompanied by a unique bugle, a kind of combination trill and quack that makes a crane’s call one of the most difficult to imitate.
Farmers Help Cranes Survive
The birds usually feed on grain early in the morning and late in the afternoon. The rest of the time is spent in so-called “loafing” areas, wet meadows where they rest up and supplement their diet by scrabbling for mice, worms, insects and frogs.
Drive down any of the two-laners that link the area’s farms, and you’ll probably spot segments of the flock, stalking about as though lords of the field. Which they are in a way, one-half the participants in what Garcia characterizes as “a win-win situation” for the avian visitors and human residents dependent on agriculture.
“The birds come in the spring before the farmers have planted, so there’s no conflict. And they come in the fall after they’ve harvested, so there’s no conflict. A lot of these farmers are switching crops – barley, alfalfa and potatoes. And when they’re rotating to a different crop, they don’t want to have a lot of waste grain sprouting the next year. So the more the cranes eat, the less (the previous grains) come up in their new crop.”
The most picturesque, close-up spot to watch the birds is an observation pull-out at the southwestern corner of the refuge. The grain field there, planted by refuge personnel, is surrounded by the Sangre de Cristo Range, dominated by massive, snow-draped Blanca Peak.
Late in the afternoon, a cacophony of cranes fly in. Wings spread, twig-thin legs outstretched, their huge feet poke out like released landing gear as they float down, a skyful of feathery parachutes. As thousands more arrive, the cranes flutter about, eating and periodically breaking into an enchanting display of “dancing.”
The mesmerizing movements – jumps, bows, a showy spread of wings – are thought to be linked to courtship and pair bonding among the cranes, which mate for life. At times, the dancing looks expert and decidedly aggressive, as a couple of cranes suddenly bound into the air, seemingly intent on vanquishing one another with an intriguing combination of grit and grace. Other times, the standoff looks so awkward and inept, the participants must surely be younger, less experienced birds having a fling with maturity.
As feeding time draws to a close, the cranes usually take off in small groups. But shortly before sunset, something – perhaps a high-flying, much-feared eagle – triggers a massive departure. Without warning, the cranes cease feeding and straighten, heads still, bodies alert. Suddenly they fly up, silhouetted against a fading sunset. As alpenglow suffuses the perimeter of peaks behind the silent, abandoned fields, the cranes slowly disappear, distant specks gracing the waiting sky.
As of July 2000, throughout the United States and Canada, there were 265 whooping cranes in the wild and an additional 122 in captivity. The main wild flock winters in Port Aransas, Texas, and the biggest concern is that a single disease or natural disaster could wipe out that entire population. For this reason, attempts have been made to establish additional self-sustaining flocks, such as an effort to integrate whooping cranes into the Rocky Mountain sandhill population.
In 1975, the U.S. Fish and Wildlife Service and the Canadian Wildlife Service began a cross-fostering experiment to see if the sandhills would raise young whoopers. Eggs from captive whooping cranes and the wild population breeding at Wood Buffalo National Park in Canada were transferred to greater sandhill crane nests at Grays Lake National Wildlife Refuge in Idaho.
Initially, the effort seemed on the brink of success, as many cross-fostered whoopers survived and migrated with the sandhills. But by 1989, no pairing or reproduction had occurred between whooping cranes, presumably because of improper sexual imprinting, a problem noted in other foster-reared species. Today, efforts to increase the number of whooping cranes have shifted to Eastern locales such as Kissimmee Prairie, Florida.
Given the similar needs and habitat of whooping cranes and sandhill cranes, why do only the sandhills seem to be thriving? Garcia says much of the answer involves disappearing wetlands.
“Both species are monomorphic,” he says, “meaning both sexes are the same color. And they don’t conceal their nests; they nest on mounds. Sandhills nest primarily in beaver ponds and forested areas, so they can somewhat camouflage (their nests). But a whooping crane, being bright white and nesting on a mound that literally can be seen forever ….”
No pun intended, the whooper eggs and chicks become sitting ducks for predators such as coyotes. “So part of what the whooping crane needs,” Garcia explains, “is somewhere that’s free of predators. And right now, the only nesting population is in Wood Buffalo National Park in northern Alberta. That park is literally thousands of acres of wetland. In some portions, there is no access by land-based predators.” But aside from a very few such sites, “These large wetlands just don’t exist any more.”
If current efforts to save remaining wetlands and establish additional populations of whooping cranes don’t succeed, there’s a sobering possibility that one day, the majestic whooper could cease to exist.
- Alamosa and Monte Vista National Wildlife Refuges, www.r6.fws.gov/alamosanwr/