19 January 2005

Save Casa Grande!

We must protect and safeguard our sacred heritage...


From Ground and Air, Prehistoric American Indian Site Under Attack
- ARTHUR H. ROTSTEIN, Associated Press Writer
Monday, January 17, 2005

(01-17) 23:48 PST COOLIDGE, Ariz. (AP) --

The four-story Casa Grande Ruins, the hand-built centerpiece of a prehistoric American Indian village, have withstood Arizona's desert sun and its rains for perhaps seven centuries.

But now those walls of concrete-like clay face an unlikely threat from the air and ground: birds and squirrels.

Cooing pigeons roost in round holes that once held a stout wooden ceiling and floor beams. The birds peck at the hardened clay and foul the ruins with droppings.

Burrows dug by the native ground squirrels hold water that undermines some of the low-lying perimeter walls in the compound surrounding the centerpiece Casa Grande, or Great House.

Officials at the ruins 60 miles south of Phoenix are pondering ways to cope with the threats and minimize further degradation of the nation's first archaeological preserve.

"It's serious if we don't deal with it right now," said Paige Baker, the monument's superintendent. If not addressed, Baker added, "Then we'll see this building start to deteriorate."

Mankind is partly to blame. The pigeons -- also finches, starlings and other migratory birds -- have been attracted to the area by ample feed available at nearby cattle feedlots, dairy and other farms.

"So the community's feeding them and then we have this absolutely fabulous place for them to sleep and nest," said Carol West, the monument's chief ranger.

At least a few dozen pigeons have adopted the Great House for their nest, and in migratory periods, starlings can number in the hundreds -- despite the presence of a great horned owl in the canopy's rafters.

"Their droppings are pretty bad, but worse than that, they enlarge the cracks and the already existing holes in the walls in order to roost and nest," West said of the pigeons.

The Casa Grande Ruins are the fifth oldest unit in the National Park Service. Some of the sites at the monument date to A.D. 550-700, while most were built between 1200-1450 by the Hohokam tribe.

A giant metal canopy has kept rainwater from pooling under the walls of the roofless Casa Grande since 1932. But while the canopy helped with long-term preservation "it provided just the perfect harbor for birds, and now they just love it and they're causing all kinds of trouble," West said.

Volunteers collect two or three gallons of debris weekly from inside the structure, looking for droppings and loosened clay to quantify how much material is being lost from the walls, West said.

"It's not difficult to imagine how, at that rate, it's accelerating deterioration of the building," he said.

The squirrels have dug scores of tunnels in the open compound surrounding the main structure and countless passages beneath much of the 472-acre complex, which is walled or fenced off from Coolidge on three sides.

The problem, West said, is that in many places, rainwater has collected in the critters' burrows beneath berm-like perimeter walls, softening them up and making them more pliable.

Also, large predators that once dined on squirrels are gone, Baker said. Only an occasional coyote still wanders through the park. Badgers are gone, as are foxes and mountain lions.

The vegetation also has changed; mesquite has given way to creosote, a desert plant that the squirrels love.

Even hawks and other predatory birds come looking for squirrels less frequently; development has "affected those migration patterns or impacted their interest in looking for prey around here," Baker said.

Increasingly, the site has become an island surrounded by urban development. A Wal-Mart and a Safeway strip mall sit on the east, across Arizona 87, and about 1,700 homes are planned to the west, said Sue Laybourn, senior planner for the city of Coolidge.

Finding a solution to the site's critter problem won't be easy, but Baker believes it can be addressed. Trapping them would be overwhelming, while poisoning has problems on several levels.

"The reason why we're here also is to protect animals, not destroy them, so that's part of the challenge. How do we do this in some manner that protects the Great House and at the same time protects the ecosystem?" Baker asked.
On the Net:

Casa Grande Ruins National Monument: www.nps.gov/cagr


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