Not that Rosen intentionally chases such pretensions, mind you. He's neither a climatologist, nor a sociologist, nor a grim security wonk. Instead, this graying herpetologist is charting the demise of Arizona's frogs. And that inquiry could hold lessons for us all.
With permeable skins and life cycles taking them from watery, vegetarian tadpole-hood to carnivorous, air-breathing adults, frogs get a buffet-sampler of our increasingly toxic world. They are also suffering the brunt of hungry, non-native animals--crayfish, game fish, bullfrogs--delivered from other climes by car, truck and train. Then there's a nasty fungus decimating their ranks, one that may have arrived with frogs shipped over from Africa. Finally, these amphibians are prey to an intense drought exacerbated by tens of thousands of new and thirsty Arizonan humans.
Capping all that is apparent apathy. Taken together, it's a pretty bleak stew. "Since we have very little in the way of active conservation programs right now," says Rosen, "we could lose all species of frogs from the state."
Drought may be the largest single factor behind their demise. While Arizona's amphibians are well-adapted to long dry spells, "they're just not ready for a drought with people having dried out the rivers, and people having brought in harmful exotic species," he says. That's especially true "for species like leopard frogs, but also for native fishes, native turtles, garter snakes and even some aquatic birds.
"The wettest habitats are already saturated with harmful non-natives, and drought compresses everything into these super-saturated habitats. So the natives are tossed into the lion's den with other species. And they just won't make it."
Frogs seem to be taking the biggest hit. That's tragic for a species that's been around for nearly 200 million years and ranks as the first vertebrate venturing onto land. Nor is Arizona alone in this primordial crisis: Around the world, some 200 amphibian species have suffered serious population drops, and up to 30 species have been reported extinct in the past decade.
Around the world, suspected causes range from shrinking habitat and pollution to climactic changes such as a shrinking ozone layer--and the resulting increase of dangerous ultraviolet rays. But Arizona's frogs also suffer from chytridiomycosis, a virulent fungus that's attacked a dozen species statewide. So devastating is chytrid that it wiped out 100 lowland leopard frogs in only two monitoring areas.
Michael Sredl is herpetologist with the Arizona Game and Fish Department. Along with Rosen and another UA herpetologist named Cecil Schwalbe, he's been studying chytrid's nasty effects. "The fungus is particularly prevalent along the San Pedro and Santa Cruz rivers in Southeastern Arizona," Sredl says. "It infects the outer layers of skin and forms a vessel in the top two layers. Then (the pustules) pop up like a sperm and swim to another host."
Just how chytrid got here is under debate. Some believe it was carried to the United States by infected African frogs, which were once quite popular for human pregnancy testing. Others believe it traveled up from Central America, where it remains widespread.
Chytrid's ultimate impact upon Arizona frog populations remains to be seen, says Sredl. "The jury is still out. But it is a very important clue--an explanation that was flying below the radar and explains many of mysterious declines and disappearances we were seeing."
Either way, the fungus is just another assault on animals that--because of their ultra-sensitivity to environmental shifts--have been called a bellwether of the planet's health. It's a bright red flag that requires rethinking our priorities, says Philip Rosen. "We've so badly mismanaged waters in the West--and are continuing to do so--that we're just not going to get species through (this drought) without actively managing them.
"From the standpoint of native fishes and native frogs, most of Arizona's streams and rivers are complete disaster areas--the worst in the world, really. In terms of fish, the Colorado River is thought by most biologists to be the single most degraded river in the world. And that's a process that's beginning to repeat itself in ever-smaller streams in Arizona."
Steps for saving the frogs range from pinpoint monitoring to establishing preserves outside of wilderness habitats, such as in ranch ponds. To Rosen, it also means so-called "safe harbor" agreements, which allow private land owners to have endangered species on their property without facing burdensome government restrictions.
Safe harbor "means you can do things to benefit a federally listed threatened or endangered species, and then go back and undo those things if you need to," he says. In other words, "you're free to increase (endangered species) populations all over your property, without the government then saying, 'Well, now that you've done this, you've got to stop ranching cattle or whatever.' It protects people who voluntarily do good things from getting wrapped up in regulations."
Just such an agreement was in the works a few years ago, when Rosen and Schwalbe hoped to establish a population of endangered leopard frogs on the Buenos Aires National Wildlife Refuge southwest of Tucson. But powerful area ranchers quickly scuttled the deal. "There were plenty of leopard frogs in the nearby Baboquivari Mountains, but we couldn't get permission to bring them to the refuge," Rosen says. "It was just politics."
It also revealed a potent political message: Any society placing tax cuts and individual property rights above everything else--including an entire species--is a society careening toward disaster. "I find it disturbing," Rosen says, "that the richest country in the world can't afford a little bit of conservation. But we're so wrapped up in our current ideology that the 'public good' isn't even properly understood as a function of government."
On this increasingly interwoven and endangered planet, saving the frogs just might help us learn that lesson all over again.