PHOENIX - The Three Fire near Roosevelt Lake scorched approximately 60 percent of an outdoor laboratory-the Three Bar Wildlife Area-that the Arizona Game and Fish Department has operated for more than three decades.

A portion of the area fence still standing is lined with burned cactus.

"The Three Bar is pretty unique. We don't know of anything quite like it," says Research Branch Chief Jim deVos. Back in 1970, the Game and Fish Department fenced in one square mile of mule deer habitat on the northern flanks of the Four Peaks overlooking Roosevelt Lake. The predator-proof fence allowed researchers to study how deer fared in the absence of animals such as mountain lions and coyotes.

In 1988, the gates to the enclosure were opened to allow animals to move in and out of the area. Then in early May 1996, the Lone Fire burned approximately half of the enclosure. So in 1997, the department once again sealed the enclosure in order to examine mule deer habitat use in predator-free environments, both burned and unburned.

The results of this leading-edge wildlife research have been reshaping how biologists throughout the country view predator-prey relationships. But the Three Fire has abruptly ended the ongoing deer study that began in 1997.

Biologists estimate that 87 deer were in the fenced wildlife area just prior to the fire, based on a count done this spring. When it looked like wildfire would engulf the valuable area, firefighters helped the department by breaching the 10-foot tall predator-proof fencing so that deer inside the enclosure could more easily escape the advancing flames.

Firefighters had some unexpected help in opening up the fence line. "A helicopter water drop also flattened a portion of the fence," says Wendell Peacock, a fire information officer working the Three Fire. Firefighters also made an extra effort to save the department's remote Three Bar cabin, located just a few miles from the wildlife enclosure.

Stan Cunningham, supervisor of the deer research project, was philosophical about the early and unexpected end of what was supposed to be a 10-year project.

"It's a happy ending," Cunningham says. "Well, not the happiest of endings, but at least due to the quick work of the fire managers and firefighters, the deer were not trapped inside the enclosure when the fire came their way."

Cunningham, who assessed the area from an airplane and on foot June 29, says he saw no evidence that any of the deer perished during the fire. "Eight of our nine radio-collared deer were still in there, even though the fence was down. It's my feeling that they probably never left, but I have no way of knowing that for sure."

What does the future hold for Three Bar?

Game and Fish biologists plan to let the fence stay down at least through this fall because the fire removed so much of the available food and shade for deer in the rugged canyon area.

"The fire burned most of the north-facing slopes, which contained the majority of the best thermal cover for the deer. That shade is extremely important to the deer, especially during times of extreme heat," Cunningham says.

Cunningham says it is unfortunate the deer study has ended. "It would have been nice to have two more years of data, but I feel pretty comfortable with what the study demonstrates: when times are good, predators don't have much impact on overall deer populations. However, when times are tough, such as during this recent drought, predators can have a significant impact on deer."