By Kevin Franklin IF WE KEEP quiet, we might see something," says Luke Evans, a University of Arizona renewable natural resources masters student. Up ahead loom the Cabeza Prieta Mountains. Like granite ships frozen in a flat sea, the mountains rise incongruously straight out of the desert floor. Centuries of tafoni weathering has worn out hundreds of smooth, pillow-sized pockets and nooks in the rock face. The Cabeza Prieta National Wildlife Refuge was established in 1939 primarily to protect populations of desert bighorn sheep. The 860,000-acre refuge also forms the Mexican border for 56 miles. In 1942, with World War II heating up, the Air Force created Luke Air Force Range (now known as The Barry M. Goldwater Air Force Range) on the refuge's north side. With a bombing range to the north and the Mexican border to the south, the wildlife refuge was effectively isolated from many of the ravages endured by other parts of the state, from overgrazing and overhunting to the infiltration of exotic plant and animal species. Today many biologists consider the Cabeza Prieta (Dark Head) refuge to be the most intact and pristine stretch of the vast Sonoran Desert. Evans and I hope to catch a glimpse of some desert bighorn sheep; but even if we remain absolutely silent, it's unlikely we'll surprise any. Historically, efforts to help the animals within the refuge focused on building or improving water tanks, including the natural tinajas (water-catching pools in impermeable stone), troughs, stock tanks and other caches. It was thought that by increasing the availability of water, the populations of sheep and desert pronghorn would also increase. The continuing collection of data on this subject is beginning to shed considerable doubt on that theory. In his paper Reassessing Fifty Years, Bill Broyles, a naturalist who knows the range better than most, points out some disparities. Water hole numbers have increased 33 percent, water hole density by 33 percent and gallons of water available by 303 percent, writes Broyles. Yet sheep and pronghorn populations remain static. In fact, biologists now believe pronghorn may never drink at all, but instead extract their water from their food and air. The additional water might hurt the natural order in the refuge. Predators like mountain lions and coyotes can now survive in the range in greater numbers, along with seemingly less-threatening creatures like European honey bees and other exotic insects. The effect of these colonizing animals on the indigenous, desert-adapted wildlife is largely unknown and unstudied. But consider the possibility of a chain reaction if a native bee that specializes in pollinating one flower is pushed out by a honey bee that fails to pollinate that flower. If that flower turns out to be this sparse environment's only source of a vitamin for some other animal, like sheep, then you can see how a serious cascade could occur. Evans measures and notes the level, if any, of water in the various tanks and rain gauges along our route. As we enter the mountains, no sheep show themselves. But neither do we see anybody else. As we hike through Smoke Tree Wash, just how remote the Cabeza is becomes apparent. We discover Evans' tracks from more than two months ago, still preserved in the sand. Only one other set of tracks appears, indicating humans have been present here for only a few minutes out of the last two months--the busy season for the refuge. Many wilderness areas in America could enjoy this same lack of human intervention. Forcing people to walk more than a few miles to their destination alleviates most overcrowding problems. Our natural wonders are probably better off without beer cans and cigarette butts. The health of the sheep populations here seem more closely connected to the exclusion of morons than the presence of water. Evans and I continue hiking toward Cabeza Prieta Tanks. As we travel we keep searching for sheep, and maybe some answers on how to ensure their continued survival here in one of the last strongholds of wilderness. GETTING THERE Hikers must write, call or fax the Cabeza Prieta National Wildlife Refuge at 1611 N. Second Ave., Ajo, AZ 85321; (520) 387-6483; or fax (520) 387-5359 and request a free permit to enter the refuge. The paperwork must then be sent back and your permit mailed to you--so it's best to plan several weeks in advance. The office is open from 7:30 a.m. to 4:30 p.m. Monday through Friday. Four-wheel drive is required in the refuge.

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