Update on the Oracle Road Animal Crossings

Pam Boedeker

Do you remember the rumors and doubts about the construction of the animal bridge on Oracle Road in 2014? There was even a cartoon of a dinosaur crossing the bridge.

SaddleBrooke Nature Club speaker, Jessica Marino, represented the Coalition for Sonoran Desert Protection. The Coalition’s mission is to protect the biodiversity of the Sonoran Desert in southern Arizona through science-based advocacy, education, and collaboration.

Ms. Marino explained the bridge and tunnel were part of a vision of the Coalition. They provide a linkage between the Tucson-Tortolita-Santa Catalina Mountains so animals can continue their migration patterns and healthy reproduction. Much research went into the location of the bridge and tunnel.

In 2009, the Coalition partnered with the Arizona Department of Transportation on a proposal to the Regional Transportation Authority (RTA) Wildlife Linkages Committee for $8.2 million to build three crossing structures across Oracle Road in the Tortolita-Santa Catalina Mountains linkage. This proposal was approved by the RTA in December 2009. Construction on the crossings began in spring 2014 and was completed in spring 2016.

The project included the bridge, the tunnel and miles of “funnel fencing” used to guide animals to the safe crossings. The fencing is nearly invisible mesh. There remain a few gaps in the fencing that are being addressed.

In 2012, the coalition began a remote camera monitoring project within the Tortolita-Santa Catalina Mountains wildlife linkage. Starting with four cameras, the project now has 17 cameras on either side of Oracle Road within protected open space. More than 30 volunteers maintain the cameras regularly and thousands of wildlife photos have been captured.

(The coalition is always seeking volunteers who will scan through those photographs.)

Since 2006, there have been over 11,000 crossings. GPS collars and transmitters have aided in the count. For instance, mule deer have been documented crossing multiple times in one week. This information helps to establish the patterns of animal movement.

Another discovery has been that different species prefer either the bridge or the tunnel. Javelina, coyote, and bobcats prefer the tunnel while the mule deer use the bridge.

Approximately 26 species have been identified using the crossings. These include the White Nose Coatimundi, badgers, mountain lions, Gila Monsters, and Gray Fox as well as the more common coyote, javelina, mule deer, raccoon, and spotted skunk.

As time goes on more crossings are expected. Each species teaches the next generation the crossing patterns. As the Big Horn population grows, they are expected to start migrating to the Tortolitas probably through the tunnel.

The crossings have been a success. More vegetation will be planted on the bridge in the near future. A Community Science Program for kids has drawn great interest. More bridges and tunnels are planned in the greater Tucson area.

Check the coalition website at www.sonorandesert.org for more information, volunteer opportunities, and great photography.

SaddleBrooke Nature Club continues to meet virtually on Zoom. Upcoming topics include our water supply.