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Tucson, Arizona | Published: 07.28.2008
One of the few studies conducted on mining's effects on wildlife found that a native desert-bighorn sheep population hung on despite the presence of a major copper mine northwest of Tucson.
The bighorns in and around the Silver Bell Mine survived.
But in general, other studies have shown that "large alterations in the landscape are not likely beneficial to most big game," said Paul Krausman, a lead author of the sheep study.
Even the bighorn sheep will likely abandon the Silver Bell area once mining eliminates more of their habitat, said Krausman, a former University of Arizona professor.
The study is becoming part of the debate today as wildlife officials and mining officials disagree over likely effects of the proposed Rosemont open-pit copper mine in the Santa Rita Mountains, southeast of Tucson.
State wildlife officials say Rosemont would be environmentally destructive. Mining company Augusta Resources maintains the disruption to wildlife and hunting would be minimal.
Krausman said he does not know the Rosemont area well enough to comment on its suitability for wildlife if it's mined.
His bighorn study examined sheep populations at the Silver Bell Mine and found 65 to 84 sheep during the 2003-05 study period. That compared with 67 to 100 sheep from 1993 to 1996, said Krausman, who is now at the University of Montana.
A longtime researcher on the effects of development and other human activities on wildlife, he was one of four authors of the 2006 study that was published in the Wildlife Society Bulletin. For many years, Krausman worked as a wildlife ecologist for UA's School of Renewable Natural Resources.
The study radio-collared eight male and six female sheep in the Silver Bell Mountains in and around the Asarco-run copper mine. Generally, the sheep stuck to desert island patches and high walls within the mine, and were not seen using mining leach ponds, pit bottoms or tailings dumps, the study found.
When and if the continued mining operations eliminate now-undisturbed desert habitat patches in the Silver Bell Mountains, it is likely the sheep also will move, Krausman wrote in an e-mail to the Star last week.
Sheep got used to human activity at the mine because of the miners' consistent behavior habits, he said.
"Sheep have been able to habituate to mines that still have good habitat features that are important, but that does not mean mines are good for bighorns," Krausman said.
Krausman and Joan Scott, of the Arizona Game and Fish Department, said they are not aware of any other studies looking specifically at the effects of mining on wildlife.
Even so, Scott said that in the Game and Fish Department's "best professional judgment, we don't believe the habitat components will exist at Rosemont for species — food, water, shelter and space."
Scott, habitat program manager for Game and Fish's Tucson office, wrote a letter this month to the U.S. Forest Service contending the Rosemont Mine would render the northern Santa Rita Mountains virtually worthless for wildlife.
The letter was one of 3,000 to 4,000 public comments the Forest Service has received on the proposed mine as it prepares to start work on its environmental review of Rosemont.
Augusta's mining plan of operations for Rosemont predicted "disruption to wildlife habitat and use will be minimal" and that the mine would not significantly reduce hunting in the area.
Company officials declined to respond in detail to the Game and Fish position because the environmental review process is just starting.
In an interview, Game and Fish's Scott said that one can always point to some species, such as bighorns, that use a disturbed habitat. By contrast, it's possible that deer and mountain lions, for instance, would need more cover than bighorns and would not do well there, she said.
Bighorns live on fairly open, barren cliffs and prefer such terrain when escaping predators. The mine probably would mimic their natural habitat, said John Windes, a Game and Fish habitat specialist in Tucson.
Deer and mountain lions need vegetation, on the other hand, for both hiding from predators and hiding to catch prey, Windes said.
Deer don't like much disturbance around them and don't like trucks driving by every 15 minutes, Scott said.
"Maybe even some bat species will use some portions of a mine," Scott said. "That doesn't mean it will provide the same sort of habitat that a natural place does, a place that has cover for most species."
● Contact reporter Tony Davis at 806-7746 or tdavis@azstarnet.com.
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