The state of Arizona spent 28 million dollars to acquire and develop the caves for tourism. The state had the advantage of avoiding the mistakes made with the development of other show caves that had been discovered many decades earlier.
With the Kartchner Caverns there was an opportunity to try to preserve them as living caves. Airtight doors, misters, a controlled lighting system, and a 3- to 4-foot-wide (90- to 120-centimeter-wide) path with 18-inch (46-centimeter) curbs are some of the measures designed to protect the caverns from tourist traffic.
"Also, every person that comes in is a little radiator giving off heat, giving off carbon dioxide and sometimes giving off extra water vapor," Toomey, the staff scientist, said.
To keep the human impact as low as possible, tour groups are limited to 20 people in the cavern known as the Rotunda Room, and 15 in the Big Room. The Big Room, Toomey added, is closed from April through September to allow a bat population to give birth and raise their young.
The bats, which begin to arrive in April, also support the caverns' living ecology. Bat guano is the sole energy source for critters such as mites, springtail insects, and cave spiders. During the winter, when the bats are absent, the insects are dormant and not bothered by tourists, Toomey said.
Toomey and his colleagues constantly monitor the caverns and surrounding area to gauge the human impact.
"We do see changes," Toomey said. "We see an increase in temperature and decrease in humidity. But we've run into some significant problems in fully understanding those."
Travous, the executive director of Arizona State Parks, explained that data on the caverns' temperature and humidity prior to their opening to the public was collected at the end of the regions' 15 wettest years in recorded history. The caverns' opening coincided with the onset of drought.
"We literally went from one end of the scale to the other," he said. "Since then, we've been trying to sort out which impacts have been ours and which is the natural scheme of things."
Toomey added that historical evidence suggests the caverns have dried more profoundly than what is happening currently. To definitively sort the human impact from the regional climate effects, the scientist is waiting for a return to wetter conditions.
Meanwhile, more than 200,000 people a year visit the Kartchner Caverns. Travous said "the whole thing was designed not to entertain so much but to instill in people the sense as they leave the park [that] it is their cave and the future depends on them."
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