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Engineering Nature at Bosque del Apache

BOSQUE DEL APACHE – Mimicking nature is Aaron Mize’s great challenge.

Up at the north end of the Bosque del Apache National Wildlife Refuge, water last week crept into the big duck pond in what refuge workers prosaically call “Unit 8.” Mize was showing off new trails built this year by refuge crews, completed just in time for next week’s Festival of the Cranes.

The trails wind through a lovely grove of cottonwoods, tracing the path of an old Rio Grande oxbow, a relic meander in a river that used to wander the floodplain here south of Socorro.

As refuge acting manager Mize, Journal photographer Marla Brose and I inched our way up the trail, the mallards and pintails already gathered on the growing wetland spooked, flying en masse to the far side of the pond.

“This has been our best duck pond on the refuge for years,” said Mize, the 32-year-old acting manager of the U.S. Fish and Wildlife Service refuge. Thanks to the new trails, the general public this year will get a look at the Unit 8 pond for the first time. It’s lovely, definitely worth the trip. But I’ve always thought the Bosque del Apache was worth the trip, one of New Mexico’s great natural treasures.

Or is it? Treasure for sure, but natural?

Spread across 57,331 acres, the wildlife refuge was formed in 1939 with a primary mission to provide habitat for the dwindling population of sandhill cranes wintering in the valley.

Ten years earlier, Congress had passed the Migratory Bird Conservation Act, authorizing the Department of Interior to create wildlife refuges for the benefit of North America’s migratory birds. In many cases at that time, there was a practical motivation. As farms spread across the continent, occupying ecosystems once used by birds, refuges became a necessity to protect the nation’s cropland from depredation by the migrating flocks.

In other cases, like the Bosque del Apache, the purpose was more direct – simply helping the birds.

And how it seems to have helped. The winter after the refuge was established, a survey found just 17 cranes, according to Mize. Last week, the official count was 7,000 cranes, and by the time the migrants have finished relocating to their winter lodgings in the Rio Grande Valley, you can expect some 11,000 cranes to winter at the refuge, with thousands more at a similar site maintained by the state of New Mexico at Bernardo, along the Rio Grande south of Belen.

It is easy to settle in along the Highway 1 ponds near the north end of the refuge, to watch the cranes flying in for the evening by the thousands, and think you are seeing one of nature’s great displays. The bugling, growing in volume as the flock grows, is one of New Mexico’s great musical extravaganzas.

But a refuge tour with Mize is a reminder that the “natural” effects visitors see are the result of intense human management.

The goal is to re-create habitats that would have been found a century ago, before humans dammed and dyked the Rio Grande into a narrow channel. A complex plumbing system diverts water into a network of ditches, delivering it to the vast wetlands that are dug and graded to mimic what the Rio Grande would have done on its own a century ago as it spread across the flood plain.

Some years, like this one, drought comes to the refuge in a way that matches what we would have seen in a drought year a century ago. The beloved “boardwalk pond” at the refuge’s south end, home to cormorants and pelicans, was nothing but cracked mud when Mize took Brose and I on a tour last week. There was so little water in the ditch feeding pond this year that it finally just dried up, Mize said.

To my look of concern, Mize responded with a wildlife manager’s calm equanimity: “Healthy wetlands are fluctuating wetlands,” he explained. “Drought is a natural occurrence. Our landscape evolved with drought.”

To the south, Mize showed us how refuge crews had cleared out unnatural thick stands of cattail that had choked one of the refuge’s ponds, taking advantage of drought to bring the system back to a more “natural” state. The pond is in an old river channel that in some years would have dried in drought, and in other years been ripped clear by spring floods. A consistent water supply has, in the past, given the pond a spectacular stand of cattails – lovely, but requiring human intervention to get “nature” back on an even keel.

Hence the dried-up pond and ripped-out cattails. “This is what Mother Nature would have done,” Mize said.

UpFront is a daily front-page opinion column. Comment directly to John Fleck at 505-823-3916 or Go to to submit a letter to the editor.
— This article appeared on page A1 of the Albuquerque Journal