A forthcoming study on wildlife linkages in the Northwest could factor into Oro Valley’s plan to annex the state land parcel known as Arroyo Grande.
The report, written on commission for the Arizona Department of Game and Fish by Northern Arizona University Professor Paul Beier, maps the dwindling pathways for animals traversing between the Tucson, Tortolita and Santa Catalina mountain ranges.
At a recent town planning and zoning commission meeting, Oro Valley officials were receptive to ideas put forth in the study to protect wildlife linkages that include Arroyo Grande, a 14-square-mile parcel north of the town.
“Instead of drawing a pretend line on the map (now) to show you where wildlife linkages will be, we’ll wait until the September meeting to have a significantly different plan,” Oro Valley Planning Director Sarah More told planning and zoning commissioners.
The significance of Beier’s study lies in that he located specific areas where wildlife crossings could be built, and identified the species likely to use these pathways.
Beier’s study proposes the installation of a series of underpasses near Tangerine and Oracle roads, and box culverts in other known crossing areas.
The study also recommends adding appropriate linkage structures over Big Wash and its tributaries as new roads are built.
The plan also calls for animal crossings to be built in the Marana area along Interstate 10. There, a series of bridges as well as smaller crossings made using box culverts or drainage tunnels would allow animals to cross the busy highway en-route between the Tucson and Tortolita ranges.
The different sizes and shapes of manmade animal crossings are important, Beier said, because of the various species the pathways are intended to protect. Some larger mammals like deer prefer crossing beneath a bridge as opposed to using use dark box culverts.
“Mule deer are not going to walk into a cave,” Beier said.
The state game and fish department had previously identified scores of wildlife-linkage areas in the state, but recognized the Tucson-Tortolita-Santa Catalina mountain corridor as one of the most crucial.
The three mountain ranges stand as a bridge, connecting large areas of open space for many animal species. If that bridge becomes impassable, many biologists say some species would be placed at risk of survival.
For example, apex predators like mountain lions and black bears have large traditional ranges. Human developments like highways present sometimes-impassible barriers within these species’ territories.
According to Beier, the Tortolita Mountains are vital to the continued health of large mammals in the region.
“If the Tortolitas become isolated, there is no way they would ever have a mountain lion or a black bear,” Beier said.
When species become isolated, their risk of disease increases as well as the prevalence for in-breeding, which can result in a host of genetic maladies including sterility.
Habitat fragmentation can result in what Beier called “demographic accidents.” He points to the Florida panther as an example.
There, rapid urban growth and habitat fragmentation pushed the great cat, the only puma species in the eastern U.S., to the brink of extinction. Biologists witnessed a dwindling number of panthers and realized the species had grown so isolated that in-breeding became commonplace. Many male panthers were born sterile.
Working with conservationists, state and federal authorities came up with a plan to restore the cat. They introduced into the area males from the Texas cousins of the Florida panther to diversify the gene pool, and had wildlife tunnels installed along the interstate where the panthers ranged.
To date, the Florida panther’s numbers have more than quadrupled, from as few as 20 in the early 1990s to perhaps 80 or more today. Beier said the animal crossings along the highway have a great deal to do with the cat’s rebound.
“I’ve been there myself, they’re full of black bear and panther tracks,” Beier said of the manmade wildlife crossings.
Conservationists envision similar crossings throughout crucial areas in Arizona.
Large mammals like mountain lions, which are not unknown to the Northwest, could benefit if local governments can mitigate the fragmentation of habitats.
In 2005, a lion fitted with a radio-tracking collar was followed throughout a vast expanse between the Catalina and Tortolita mountains. The cat made frequent crossings of the proposed annexation area, and was tracked skirting Oro Valley town limits.
While the cost to build a series of animal crossings would potentially be great, there are options for funding. One is the voter-approved Regional Transportation Authority. The 20-year roadway improvement plan set a $45 million budget for building wildlife crossings.
Beier’s plan integrates wildlife linkages with fencing to help funnel the animals to the pathways.
A similar project has been completed on State Highway 260 in the White Mountains, where elk crossings were constructed to help prevent animal-auto collisions.
There, instead of fencing, Beier said large rocks and boulders were used to funnel the animals into the crossing area. The use of natural material was for aesthetic purposes, but still creates a barricade the animals are unlikely to cross.
While the future of animal crossings in the Northwest is yet unclear, Beier remains optimistic, noting the changing attitudes of many elected officials.
“They are increasingly aware,” Beier said.
Oro Valley officials remain in the early planning stages of the proposed annexation area, but have expressed willingness to work with conservationists to protect wildlife.
Animal species that would benefit from wildlife linkages in study area:
Mammals: Black bear, bobcat, badger, mountain lion, javelina, kit fox, mule deer.
Reptiles: Gila monster, desert tortoise.
|Land protection close to vote
A campaign to have an initiative placed on November ballots came one step closer to fruition last week.
The proposed ballot measure would change the Arizona Constitution, allow altering of the Arizona State Land Department and put more than 570,000 acres of state holdings into permanent protected status — including more than 6,000 acres of Arroyo Grande, the state parcel north of Oro Valley.
Backers of the proposed initiative, spearheaded by The Nature Conservancy, gathered more than 350,000 signatures from residents across the state. Last week, signatures were turned in to the secretary of state’s office for verification.
A local conservation group, the Coalition for Sonoran Desert Protection, aided in the signature drive, collecting more than 3,000 from Oro Valley alone.
“I feel very optimistic that this is going to pass,” said coalition director Carolyn Campbell.
If the measure does pass in November, it would mean a significant change to the land department, which was established at the time of statehood in 1912.
At the time, the federal government gave the department more than 12 million acres of land to use for the purpose of raising money for state schools. The department now manages about 9 million acres of land.
The department has generally leased lands to ranchers, or sold parcels at auction to raise funds. The proposed initiative would allow the department to sell the land to local governments for open space use at appraised value, rather than to the highest bidder. The initiative proposes allowing the department to bypass the auction and sell directly to local governments.
The plan would also mandate the land department to work with municipalities on development plans for state parcels. Another proposed change would allow the department to use land-sale proceeds for operational expenses.
Currently, most sale proceeds go to schools districts.