Seeking safe passage home

Seeking safe passage home
Protecting animal crossings presents a challenge in proposed Arroyo Grande annexation

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By: Patrick McNamara
March 26, 2008

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At the northern edge of Oro Valley, standing on the Oracle Road shoulder, Carolyn Campbell points to the

pavement.

“When we see roadkill, that’s the good news,” she said.

While not excited about animal fatalities, Campbell, who heads the Coalition for Sonoran Desert Protection,

said carrion found on or near highways indicates that animals at least still attempt to cross.

It’s important evidence that animal populations have persevered in the face of encroaching development. But

Campbell fears that nature’s resolve may soon be pushed to the brink.

“The largest cause of habitat fragmentation in the Southwest is urban growth,” Campbell told the Oro Valley

Town Council at a recent meeting.

Campbell came to advise the council on wildlife corridors, especially as they may relate to the town’s

possible annexation of Arizona State Trust Land north of Oro Valley, some 14 square miles of desert called

Arroyo Grande.

Conservationists like Campbell consider Arroyo Grande to be crucial habitat for some of the Sonoran Desert’s

unique wildlife species, but fear poorly planned development would harm the area’s fauna, including mule deer,

mountain lions and bobcats, javelina and scores of desert reptiles.

Fragmentation occurs when roads, neighborhoods and other man-made features fracture the continuity of natural

landscapes. Such fragmentation cuts into animal habitats and often leaves species isolated, unable to move

throughout their range.

“In these areas, you’re looking at specific animal species that need to get from one area to another,” said

John Shepard, deputy director of the Sonoran Institute, a conservation group based in Tucson.

Arroyo Grande happens to be flanked by two key wild areas — the Santa Catalina and Tortolita mountain ranges.

Wildlife researchers say Arroyo Grande and its washes and desert tracts serve as important corridors for

animals moving from one mountain range to the other. Inevitably, the animals end up crossing Oracle Road.

Clogging the corridor with development could put animal species at risk. It would segregate breeding

populations and limit the diversity of gene pools, Shepard said.

Campbell wants wildlife corridors identified and protected in the planning stages of Arroyo Grande, as the

town and state land department hammer out a pre-annexation agreement.

A possible strategy to preserve corridors and prevent fragmentation would involve keeping development away

from recognized animal pathways.

For Arroyo Grande, that could mean concentrating development in the northern and eastern portions of the

property. Doing that would leave an unmolested expanse between the mountain ranges that animals could

traverse.

In addition to clustering development, Campbell would like to see bridges built at strategic intervals along

Oracle Road. These spans could provide safe conduits for animals passing underneath the road.

“What we’re talking about with ADOT (Arizona Department of Transportation) is having span bridges,” Campbell

said.

The state agency already plans to widen portions of Oracle Road in northern Pima County. Campbell says that

building bridges over known animal crossings could eliminate roadkill and mitigate habitat fragmentation.

In 2004, ADOT conducted a roadkill study on 20 miles of roadways throughout the Tucson area, including a

portion of Oracle Road near Arroyo Grande. The study found that during 34 days in the study area, vehicles

struck 2,500 animals. That figure included mostly smaller animals, such as reptiles, rodents and birds. But

larger creatures, including mule deer, coyotes and javelina, also perished on the pavement.

Under Oracle Road, near its intersection with High Mountain View Place in Oro Valley, a small wash runs

westward into Big Wash, a likely animal crossing hot spot, Campbell pointed out during a tour of potential

wildlife linkages in the Arroyo Grande area.

Building a bridge there, and elsewhere along Oracle Road, as well as planting vegetation in the areas

underneath them, would present animals with clear routes between habitats.

Finding the money to do so may prove challenging, but Campbell thinks it could come from various sources, like

the Regional Transportation Authority. The voter-passed RTA allocates $45 million for transportation-related

wildlife linkages.

To date, few municipalities have submitted proposals to the authority for such projects, said Dennis

Dickerson, environmental planning coordinator with the RTA.

ADOT, too, recognizes the desire of many to protect species and habitats.

The department’s 2006 “Arizona Wildlife Linkages Assessment” identifies 150 potential wildlife linkage zones,

including Arroyo Grande.

“If integrated into regional planning frameworks, these areas have the potential to be maintained or preserved

during this time of prosperity, growth and development,” the study reads.

Shepard lauds the state’s recognition that corridors exist and merit protection.

“It’s a tremendous step forward,” Shepard said. “Our feeling is that planning needs to happen on a large

scale.”

As Oro Valley officials begin pre-annexation negotiations with the state land department, Campbell and others

hope the town will adopt the guidelines spelled out in the county’s Sonoran Desert Conservation Plan. The

county’s plan includes allotments for wildlife corridors.

“A lot of the policies that they’ve made can be readily adopted by Oro Valley,” Councilman Barry Gillaspie

said.

The councilman said he and town officials are committed to preserving open space in Arroyo Grande, and to

strengthening conservation measures.

“I’m positive that we will be able to follow through with the Sonoran Desert Conservation Plan,” Gillaspie

said. “We’re going to work very closely with Pima County.”

Campbell, too, anticipates working with the town during the annexation process.

“I’m excited to be working with you,” Campbell told the council recently, but added, “I’m not excited about

developing the land.”

 

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