The Sonoran Desert currently faces a major landscape connectivity challenge: The Tucson and Tortolita Mountains are currently divided by the 10-lane Interstate-10 freeway (I-10) and the parallel frontage road and railroad. These mountains are ecologically important and home to diverse species, including animals like kit foxes, mountain lions, and Sonoran Desert tortoises.
“Wildlife linkages” are landscape connections that allow wildlife to move freely, as they need, to find food and mates, and encourage genetic diversity. Due to extensive man-made barriers, it is almost impossible for wildlife to navigate through the Tucson-Tortolita linkage.
The preservation of the Tucson-Tortolita-Santa Catalina Mountains wildlife linkage has been a priority of the Coalition for many years. A lot of progress has been made, including the successful Ann Day Memorial wildlife bridge and underpass on Oracle Road, and preservation of open spaces such as Cascada and El Rio Preserve. The Coalition is now shifting our focus to the Tucson-Tortolita linkage to continue towards this larger goal, building on the successes from our advocacy and land-use policy work preserving the Catalina-Tortolita wildlife corridor and the Oracle Road wildlife crossings.
Photo credit: Map and imagery data: Google, Airbus, Vexcel Imaging US, Inc., 2025. Additions by CSDP.
History
In 2001, the Pima County Board of Supervisors adopted the award-winning Sonoran Desert Conservation Plan and updated the Pima County Comprehensive Land Use Plan using the science team’s biological map. This map, called the Maeveen Marie Behan Conservation Lands System (CLS), ensures that biologically important habitats are protected and development is managed responsibly. Outlined in this map are six “Critical Landscape Connections” – areas where connectivity is threatened but can still be protected and reconnected through proper planning and management. One of these Critical Landscape Connections is between the Tucson and Tortolita Mountains, also known as the “Tucson-Tortolita linkage.” Due to the nearly impassable nature of I-10 bisecting this linkage and the increasing isolation of the Tucson Mountains from a variety of development pressures, we are now shifting our focus to the reconnection of this linkage.
Survey data reveals low wildlife movement
In February 2021, the Coalition began a new wildlife camera study, both east and west of I-10, of species movement and presence between the Tucson and Tortolita Mountains. In 2023, we expanded this study with walking roadkill surveys in a one mile stretch along Twin Peaks Road at Rattlesnake Pass, as well as driving roadkill surveys on I-10 and the frontage road between Cortaro Farms Road and Tangerine Road. Read the full report here.
The suggested result of these surveys is alarming: that I-10 and the frontage road act as a nearly impassable barrier to wildlife movement.
- Only one coyote was documented during a 7-day roadkill survey. This could mean animals are rarely attempting to cross over the freeway or frontage road.
- Our wildlife camera data concludes that ringtails and hooded skunks were only documented west of I-10, and kit foxes were only documented east of I-10. We believe that these wildlife populations have become isolated after not moving between the Tucson and Tortolita mountains in a very long time.
- The only way across I-10 is a single abandoned railroad underpass, which remains difficult for some species to navigate due to the concrete barricades placed to prevent vehicle traffic. However, ADOT has future plans to remove this underpass to use the soil for a nearby interchange.
Within another 20-30 years of development, there is a high risk of wildlife populations in the Tucson Mountains becoming completely isolated.
How can we connect the Tucson and Tortolita Mountains?
- The newly built Santa Cruz River Wildlife Ramp will help wildlife traverse the river and its steep levees. Wildlife funnel fencing will guide wildlife through this passage.
- A wildlife bridge over I-10 at Avra Valley Road would allow wildlife to fully move between these mountains.
Pieces are already moving into place – Pima County completed construction of the Santa Cruz River Wildlife Ramp this summer. In 2022, the Coalition for Sonoran Desert Protection and the Arizona Game and Fish Department collaborated with Pima County and Solis Engineering to ensure that the ramp was designed to meet the specific needs of wildlife in the area. This is a major step forward! When connected to a future wildlife bridge through wildlife funnel fencing, these crossing structures will finally reconnect the landscape, reclaiming habitat and a pathway in and out of the Santa Cruz River.
How you can help
- Stay informed! Sign up for our emails to get the latest updates
- Get involved! Attend one of our events, such as our highway cleanups near the Santa Cruz River Wildlife Ramp. See available dates here!
- Submit a Letter to the Editor (LTE)! Share your opinions in favor of wildlife crossings and a protected and connected Sonoran Desert with the Arizona Daily Star. Your letter doesn’t have to be long — a few sentences to a paragraph will do! If you agree with any of the points below, feel free to incorporate them into your message:
- I want to see more crossings where they are needed most in the Sonoran Desert.
- I voted in favor of the 2006 RTA Plan sales tax for the wildlife crossings, and it’s great to see these positive outcomes from the public’s vote and investment.
- Crossings like these improve road safety by reducing wildlife and vehicle collisions, while also supporting the genetic health of wildlife populations across broken landscapes.
- Wildlife in our backyards can’t be taken for granted. Projects like this are needed to build the community we want to live in in the future.
- Wildlife crossings are great fixes to roads that are already built, but are not a substitute for open space protection. We need both wildlife crossings and protected open spaces.
The next RTA Next plan will head to voters in March 2026, asking the community to vote on a half-cent sales tax that will continue funding transportation projects through 2046, including a $50 million budget for wildlife linkages. There was nearly ten times as much community support for wildlife crossings than for any other item in the RTA Next! This is a once-in-twenty-year chance to secure funding for additional wildlife crossings in Southern Arizona, and we’re counting on the community to make it happen!
