By Andrew Stuart
They sail in on wingspans of 7 feet, arriving in groups of three and four. The massive birds stake out their roosts for the night, and they jostle, cry and call.
As the sun sets, the assembly swells into the thousands. The birds’ wild, rolling cries fill the sky. Visitors look on from just a few yards away.
It’s like something out of an African safari. But this scene – one of the planet’s great natural spectacles – is in the Chihuahuan Desert.
Bosque del Apache National Wildlife Refuge, on the Rio Grande near Socorro, New Mexico, was created as a sanctuary for migrating waterfowl. Each winter, it’s home to as many as 15,000 greater sandhill cranes, tens of thousands of geese and 20 species of ducks.
In southern New Mexico, the Rio Grande enters the epic austerity of the Chihuahuan Desert. Lechuguilla and ocotillo cling to its banks. Ranges of desert mountains shape its course.
Yet, for thousands of years, wintering birds have been drawn to this harsh country. Sandhill cranes from the Northern Rockies. Snow geese, Ross’s geese. Ducks from the Great Plains.
What brings them to the Middle Rio Grande?
Amanda Walker is a park ranger at the refuge. She said wetlands here are ideal roosting spots for cranes and geese. And at the refuge, birds can replenish after long migrations.
“Well, there’s a lot of food here,” Walker said. “Sandhill cranes are looking for things under the ground, like tubers and roots, seeds even. They’ll also eat mammals and snakes. And they can find that here. And nearby, they can also find their roosting spots. Here, at Bosque del Apache, they’re able to find those things very close together.”
The migration is an ancient one. Native American hunters took advantage of the annual abundance. Ancient rock art depicts cranes and geese.
But beginning a century ago, the construction of dams transformed the river habitat. Historically, the river surged over its banks each year, swelling with spring snowmelt and then with summer rains. The flooding created wetlands – waterfowl habitat. But dams ended that pattern.
Conservationists recognized the need to intervene. In 1939, Bosque del Apache was created – to ensure habitat for migrating birds.
Recreating ancient conditions in the absence of natural floods is no simple task.
The refuge spans 57,000 acres. But its core is the river’s historic floodplain. In this 9,000-acre stretch, staff have created 50 “wetland units.” Each fall, a number of these units are filled with water diverted from the Rio Grande. Other units are tilled and plowed – allowing the birds’ food sources to grow.
For sandhill cranes, a favorite native food is yellow nutsedge, or chufa. The cranes use their sharp bills to dig up the plants’ buried nutlets. Ducks feast on grains and grass seeds, then shift to insects later in the winter.
Sandhill cranes were near extinction a century ago. Their numbers are strong now. But Walker said refuges are still critical to their survival and health.
“They still need wintering habitat,” Walker said, “and it’s becoming trickier to find, with changing landscapes and habitat and climate, so the stopover sites that do exist become a lot more important. So even if their population isn’t necessarily declining, the places that they do go elevate their status, because there are so few of them.”
Historically, birds would have exhausted food supplies in one area, then moved on to another. Waterfowl now have limited options. Refuge staff work to provide a food supply adequate for the entire winter.
They grow sweet corn. Wary of predators, cranes won’t enter standing corn. But every week or so, refuge staff knock over a few rows – and cranes and geese feast.
The great bird display lasts from October to February, and draws more than 100,000 visitors.
The chance to see such a density and diversity of birds, at such close range, sets this Chihuahuan Desert refuge apart.
“You can go to lot of different places and see sandhill cranes, or different species of ducks, or snow geese,” Walker said, “and in some places you may have a similar experience, but you can see all three of those groups here, really close up. I think that’s what draws a lot of our visitors, is that they can experience sandhill cranes from me to you, within their car, and it’s bizarre, but really cool too.”