With its re-emergence in 1996, the exotic jaguar became a cause celebre in the Southwest and beyond. No fewer than five private groups have detection or conservation projects in the United States and northern Mexico.

 Defenders of Wildlife reports a population of 70 to 100 jaguars some 120 miles south of the U.S. border in the mountains of Sonora, where wildlife reserves have been established. Activists are attempting to acquire tracts of land to create an even larger jaguar haven. This Sonoran community of cats almost undoubtedly produced Macho A and B - along with any other jaguars that venture into the United States.

 Although the Mexican government professes a commitment to protecting jaguars and their habitat, nearly all the concerned conservation groups contend that jaguars are still being hunted and killed in Mexico, primarily by landowners and livestock interests.

 As the conflict over critical habitat suggests, the proliferation of conservation groups has created tension.

 McCain and Childs say media-savvy organizations such as the Center for Biological Diversity and Defenders of Wildlife, while toiling on noble projects, make it more difficult for the borderlands jaguar project to garner funds needed to maintain its research. They say their work has been appropriated in some cases, their jaguar photos used by other groups to tantalize donors.

 "The jaguar gets everyone excited," McCain says. "Everybody wants a piece of the jaguar. The other groups have all got several people working on the issues. They end up getting the available funding, and it's not going for jaguar conservation."

 At least, not for the program McCain predictably sees as most vital - his. He wants to expand the Borderlands Jaguar Detection Project's camera program to determine if Macho B has company inside the U.S. The project's study area has monitored portions of three mountain ranges. Based on sightings and habitat modeling, McCain believes 10 ranges in Arizona and New Mexico should be studied.

 He'd also like to fit jaguars with radio collars to better grasp their ranges and habits. A radio collar would help identify the most crucial habitat - including the valleys that connect the mountain ranges. He knows Macho B traverses these lowlands, sometimes crossing highways, because he's photographed the cat in separate mountain ranges. "If anyone knows good jaguar habitat, it's him," McCain says of Macho B.

 Other conservation groups, however, have vigorously opposed a capture-and-collar effort, he says.

 Border fencing makes acceleration of the borderlands jaguar project's photographic survey more crucial, McCain says. "We've only surveyed 12 percent of the jaguar's suitable habitat in Arizona," McCain says. "This is the time to step that up."

 And what's preventing that from happening?

 "I need some cash and some help. This is beyond the scope of what Jack and I can do on our own," he says. "It would take a team of six or eight people, rather than one or two."

The borderlands jaguar project subsists on an annual budget of about $150,000, the lion's share spent on camera equipment. Childs notes that funds arrive in $10,000 or $15,000 increments. He and McCain say they'd prefer to spend their time in the field rather than trolling for donations and grants. (Some of the fiscal difficulty may be of the project's own making; it is not yet set up as a nonprofit.)

 Robinson of the Center for Biological Diversity bristles at the suggestion that any group is detracting from any other. He notes that his own organization is in a constant scramble for funding, but has donated to others working on jaguar conservation projects. He says he admires what the BJDP is accomplishing. Like McCain, he wishes its camera-trap program could be expanded. "Their photos have been a tremendous boon to the jaguar," Robinson says.

The urgency of the fencing issue might serve to unite the sometimes-fractious factions in the jaguar detection and protection effort. "I'd like working with all these groups to stop this fence," Childs says. "I'll try my hardest to stay with the science and give real reasons why this fence is going to be so harmful."

 But even if environmental groups defy extreme odds and successfully oppose expanded border fencing, an inherent dissonance would abide: Should the main effort and funding be directed toward the study and tracking of jaguars, in hopes that more information will lead to effective conservation? Or will a substantive return of the jaguar require a formal reintroduction effort that has the potential to make jaguars as contentious a subject as reintroduced wolves?

Until the Center for Biological Diversity lawsuit is resolved, the jury considering the question will be - almost literally - out.

In the meantime, the fate of the jaguar in the U.S. would seem to depend on the survival of the population in the mountains of Sonora. This is why myriad conservation groups - among them the Northern Jaguar Project, Sky Island Alliance, Defenders of Wildlife and Mexico's Naturalia - are concentrating on preserving and building that community of cats.

McCain lives in a century-old adobe, once the hub of a working ranch, that appears to be melting into the landscape. To the east looms the rocky rampart of Atascosa Peak, a 6,235-foot butte topped by an old fire lookout. Author and naturalist Edward Abbey kept watch there in the 1970s. A concrete stock tank that serves as McCain's swimming hole has also slaked the thirsts of desperate migrants.

 McCain stays here for free; in return, the rancher gets a watchman of sorts for his property, a private parcel within Coronado National Forest. McCain's only steady companion is a yellow Lab-chow mix named Poncho. The dog, which possesses the black tongue and impressive brow of a chow, was discovered wandering in the desert by McCain's nearest neighbor, some 10 miles distant.

 "I'm a full-blown hermit," McCain says. "I live a pretty frugal life to do this. I didn't earn enough to pay taxes for the past two years. But I'd like to do this for 30 or 40 years - as long as I can."

 Of all the places he's tracked predators, this is his favorite.

 "I've never fallen in love with a place like I have here," he says. "The ecology is so specialized. It just blows you away. Everything is alive, and there are more incredible ecological interactions going on here than one can comprehend."

 Despite countless hours traversing these canyons, he's never beheld a jaguar in the flesh - at least not in Arizona.

 McCain has, however, trapped live jaguars in Sonora, using leg snares. He was working for another organization, attempting to affix radio collars to the cats so their movements could be documented. Unfortunately, he says, he lacked the proper resources - specifically, a dart gun. He was forced to rig a tranquilizer syringe on the end of a branch to administer the knockout shot. One of the jaguars died in the process, he laments. He left the project before he could track the other.

 "The mortality was completely avoidable, if we'd been properly prepared. That was not an easy thing to deal with," McCain says.

 But his confrontation with the agitated jaguar will not be forgotten.

 "Trapping a jaguar is intense," says McCain, who has also caught mountain lions. "A trapped lion just wants to get away. A jaguar goes away from you as far as it can, only so it can get up more speed to charge you. They're very shy until they have you in their space. Then they put their ears back and let you have it."

 I ask if the phantom Macho B is aware of McCain's presence.

 "I'm pretty sure he is," McCain replies, who's been near enough to Macho B to study fresh tracks, scat and other signs. "I've been very, very close to Macho B. I know he's seen me. I just haven't seen him."

 But there's another reason McCain is certain the jaguar known as Macho B has been watching. "You can sense a predator's presence," the researcher says. "You can't deny it."

 The author lives in Phoenix.