The Horseshoe 2 Fire burns on May 8, 2011, as seen from Hwy 80 and Portal Road, looking west. Photo by Michelle Fidler, U.S. National Park Service

Firefighters ordered evacuation of the Southwestern Research Station and private homes near Cave Creek Canyon Sunday as the Horseshoe 2 Fire, driven by wind and fueled by tinder-dry pine needles and brush, advanced on a canyon known as the crown jewel of the Chiricahua Mountains.

Firefighting crews also wrapped the historic Cima Cabin, built as a fire camp by the Civilian Conservation Corps in 1934, in flame-resistant material and prepared to set back burns to slow the advance of the fire.

As of last night, the human-caused fire, which began May 8, had burned 26,542 acres in the Chiricahuas, about 100 miles southeast of Tucson. It is 20 percent contained.

On Sunday, fire entered the South Fork drainage of Cave Creek Canyon, home to a diverse population of flora and fauna, including the densest population of nesting raptors in North America.

Nine helicopters dropped water to slow the fire's advance. Firefighters also set fires on some ridge tops, allowing a slow downhill burn.

A similar strategy will be used around the structures being defended, said Karen Takai, spokeswoman for the 600-member interagency team fighting the fire.

Crews planned to set back burns as early as today to create a slower, less destructive burn around the homes and buildings that were evacuated Sunday. The most recent evacuation was a "strategic maneuver" so firefighters could clear brush and begin the back burn as soon as weather conditions are right, fire spokeswoman Michelle Fidler said. Winds are expected to pick up over the next few days and peak at 35 to 40 miles per hour by Wednesday.

"We want it on our own terms, so doing a burnout is one way to do that," Takai said. "You can wait for the fire just to come through at its own speed, but at that point, you're talking about a hotter fire."

Takai said about 20 researchers and visitors left the research station early Sunday, and the five permanent staff members were ordered out in the afternoon. Cave Creek campgrounds and the bed and breakfasts in Portal host visitors from around the world.

Firefighters had a significant victory Sunday when they used back burns to stop the fire from spreading southward, Fidler said.

The region is the northernmost range for many species of bird, including the elegant trogon.

"It's the crown jewel of the national forest here," said naturalist Narca Moore-Craig, who lives in Portal. "It has the largest density of raptors in North America, by a factor of five over the next-best place."

Moore-Craig and her husband evacuated on the fire's first night. It grew fast, not even visible when she went to bed that night. "An hour later, there were flames on the ridge."

The fire continued to grow Sunday, with humidity in single digits and wind gusts of up to 25 mph, Takai said. Moore-Craig feels safe now, back in her home, which the fire burned by. "I'm worried about my neighbors," she said. "Things are really bad here in Portal."

Did you know?

The Southwestern Research Station - five miles from Portal - is an arm of the American Museum of Natural History in New York and has been the site of biological, anthropological and geological studies since 1955.

Reporter Kimberly Matas contributed to this story.