Maintaining a Sandhill Crane Oasis in the Desert

In a New Mexico desert transformed by human activity, wildlife managers create the seasonal wetlands that sandhill cranes rely on each fall and winter

By Allison Torres Burtka
Conservation
Sep 26, 2024

Backlit by the setting sun, sandhill cranes alight on shallow water in New Mexico’s Bosque del Apache National Wildlife Refuge. (Photo by Jack Dykinga/Nature Picture Library)

AS THE SUN STARTS TO RISE on a cold January morning in New Mexico’s Bosque del Apache National Wildlife Refuge, dozens of sandhill cranes huddle together in a small wetland. Standing in still water that rises halfway up their long legs, the birds are asleep and nearly motionless. Soon they begin to wake up, ruffling their feathers and calling to each other before stepping out of the water onto ice that has formed around them overnight. Then they take flight, a few at a time.

Each fall through winter, tens of thousands of cranes stop here at the refuge, some 95 miles south of Albuquerque, or at other watery sites within the state’s Middle Rio Grande Valley. The birds rely on these wetlands in the desert for seeds, tubers, small animals such as frogs and other foods. They also need a secure roosting habitat where potential predators can be seen or heard from the safety of the water.

New Mexico’s seasonal cranes belong to the species’ Rocky Mountain population. Numbering roughly 27,000 birds, it is one of six migratory sandhill crane populations scattered across the United States. (There are also three nonmigratory populations.) The range of the Rocky Mountain cranes stretches from Montana, their northernmost breeding grounds, to their southernmost wintering grounds in Mexico.

Nearly all of these Rocky Mountain cranes make a stop in the Middle Rio Grande Valley. “It’s just like a funnel,” says Alan Hamilton, president and founding director of the nonprofit Rio Grande Return. “They come from all these nesting areas in the north and funnel down through this narrow area in New Mexico.” The cranes can fly 50 miles per hour and cover up to 400 miles in a single day. About 80 percent of the birds will stay in the valley until spring, while the rest continue their journey to spend the winter in southeastern Arizona or Mexico.

Near the refuge visitor center, a group of sandhill cranes (above) feeds and shelters just after sunrise in a small pond. Such wetlands, which the cranes rely on, were once natural but now must be created by wildlife managers who direct water through a series of canals (below) located throughout the refuge.

“Modern-day pterodactyls”

At 4 to 5 feet tall, the sandhill crane is a striking bird, with bright red feathers at its crown and a wingspan of up to 6.5 feet. It is also among the oldest living bird species, having survived for millions of years—up to 10 million by some estimates. The cranes in fact look a bit like dinosaurs. “I call them modern-day pterodactyls,” says Dan Collins, a migratory game bird biologist with the U.S. Fish and Wildlife Service (FWS) Southwest Region Migratory Bird Program. “Outside of alligators, it’s the closest relative to a dinosaur.”

An image of orange reeds alongside a small irrigation canal.

Sandhill cranes also sound different than typical birds. Their calls are loud and distinctive. “It’s like a rattle mixed with a song,” says Deb Caldwell, executive director of Friends of Bosque del Apache. When Collins handles cranes to put tracking devices on them, he says, “they gurgle, and they grunt, and they growl, because of the way their trachea is situated.”

Sandhill cranes are the most abundant crane species in the world today. Yet these long-term survivors nearly went extinct in North America during the early 1900s, victims of habitat loss and, especially, overhunting. Thanks to hunting regulations along with habitat protection—many of these efforts under the auspices of the Migratory Bird Treaty Act of 1918—the species bounced back. Its total population is now estimated at more than 1.4 million birds, and the crane’s recovery is considered one of the greatest U.S. conservation success stories.

Although most of the crane populations remain stable or are increasing, the species’ long-term survival is far from guaranteed in today’s rapidly changing world. Habitat loss and water diversions for development are the biggest threats, especially in habitats critical to large numbers of the birds, such as the Middle Rio Grande Valley.

In addition to sandhill cranes, hundreds of other wildlife species benefit from Bosque del Apache’s carefully crafted wetland habitats, including the threatened yellow-billed cuckoo (above) and the endangered New Mexico meadow jumping mouse (below).

Mimicking nature

Historically, the Rio Grande created the seasonal wetlands that cranes rely on in the valley. But as the region’s population boomed, and commercial agriculture and other development took off, more and more water was allocated for human use. In the 1950s, the valley’s stretch of the river was channelized, its once broad, free-flowing waters reined in and straightened by levees into a relatively narrow channel. “Essentially, it was cut off from those ecosystem processes it was influencing throughout the valley,” explains Amanda Walker, a Bosque del Apache park ranger.

Today, it’s up to wildlife managers to create the wetlands the cranes need. Their goal is to manage the landscape to mimic conditions that would exist if the Rio Grande still ran wild, primarily by directing water strategically through a system of constructed ditches and canals. While the state and several regional entities also manage wetlands to support cranes and other migratory waterbirds, Bosque del Apache is by far the valley’s most heavily managed desert wetland habitat.

An image of New Mexico meadow jumping mice.

Management strategies differ depending on the season. “During the summer, moist soil and wetland management units are strategically flooded and dried, and that encourages seed production from naturally germinating annual plants. And then those native seeds are later food for wildlife in the winter,” Caldwell says. By way of the canals and ditches, “the water can be moved around as the waterfowl finish feeding in one place” and move to another.

The work can be challenging. “We’re talking about wetlands in the desert, so we have to be really creative and very strategic about how we use water on the landscape,” Walker says. Water that flows into the refuge from the north—provided through a ditch system managed by Middle Rio Grande Conservancy District—can be unreliable some times of the year, for example. When that happens, refuge managers must supplement the supply by pumping up groundwater from a series of wells.

Cranes and other waterbirds are not the only wildlife that benefit from this complicated system. Hundreds of other species make their home at the refuge either full or part time, including four at-risk species: the New Mexico meadow jumping mouse, the southwestern willow flycatcher and the Rio Grande silvery minnow—all endangered—and the threatened yellow-billed cuckoo.

Two cranes tussle during a feeding bout in the refuge. Now that the region has lost the natural flow of the Rio Grande, one of refuge managers’ greatest challenges is preventing the habitat’s progression from the grasses cranes feed on to woody shrubs and trees.

Halting the march of succession

When the valley lost the natural flow of the Rio Grande due to human development, it also lost the powerful ally that kept much of the surrounding landscape in an early stage of ecological succession—annual grasses—needed by cranes and other waterbirds. Among the challenges refuge managers face today is preventing the habitat’s progression from those grasses to woody shrubs and eventually to trees.

“A wild river would set back succession in patches throughout its floodplain,” says Walker. Because the river would not spread across the landscape the same way each year, “some woody areas would be able to mature, while others would be cleared, making way for early successional grasses. Major flood events would take out older trees, while regular flooding would clear out understory. We do that now with heavy equipment and other tools,” she explains. Strategies for maintaining grasses include prescribed fire (both to set back tree growth so that grasses can grow and to remove invasive species), mowing some areas to give birds access to seed, and tilling the soil to allow the annual grasses and other plants favored by cranes to flourish.

What would happen if the refuge were not managed this way? “Because we’re cut off from water, succession would occur, and it would become a very woody habitat, probably many more invasive plant species moving in,” Walker says. “The seasonal wetlands at Bosque del Apache specifically would pretty well cease to exist, because there’s no water to feed them without the ditch and canal management that we do.” The result: Tens of thousands of sandhill cranes would lose their most essential fall and winter habitat.

A flock of sandhill cranes feeds at sunrise in the refuge. Because the birds are so big and striking, they are popular with visitors whose support may help secure much-needed funding to manage the habitat.

Cranes as ambassadors

Creating and maintaining Bosque del Apache’s wetland habitat has required major collaboration between FWS and a number of federal, state and private partners. Through the Intermountain West Joint Venture, several additional states, Canada and Mexico, Indigenous Tribes and private landowners—primarily farmers and ranchers—also collaborate to protect habitat throughout the entire range of the sandhill crane’s Rocky Mountain population. Over the past 25 years, an increasing number of participating landowners have agreed to preserve wetlands on their property through conservation easements.

“These diverse partnerships are key to getting the funding needed for further restoration and management of wetlands on Tribal and private lands, and on our state and federal wildlife refuges as well,” Hamilton says. “It’s been one of the successes we can point to in the conservation world as really having worked.”

Still, managing Bosque del Apache’s wetlands is “becoming more and more difficult because the refuge faces new challenges with climate change—longer periods of hot, dry weather—and a river that’s more heavily taxed by a growing population,” Caldwell says. Refuge managers are also faced with dwindling federal funding for their work.

Caldwell says the cranes are the best ambassadors to increase financial and other support for the refuge. As tall as people, the birds are easy to spot. You don’t need a guide like you would to find a tiny bird high up in a tree, she says. For this reason, Caldwell calls the sandhill crane an “entry-level bird” that people notice and pay attention to—attention that may lead to a new interest in birding as well as more support for the habitats birds need.

Such deeper appreciation of the natural world would be beneficial for people themselves, says Hamilton. “We’re not just doing this to help the cranes and to help the waterfowl and help the ecosystems,” he says. “We ourselves need these for our own well-being—our own psychic, soulful, well-being. We need these animals as much as they need us right now.”

NWF priority

Restoring Wetland Habitat

The New Mexico Wildlife Federation (NMWF), a National Wildlife Federation affiliate, helped restore more than 5,000 acres in the refuge and across the Middle Rio Grande Valley. Rio Grande Return’s director, Alan Hamilton, formerly of NMWF, led many such efforts, calling the wetlands “among the most critical natural resources we have in New Mexico.”

Read more about Allison Torres Burtka.