Monitoring results from the Tangerine Road wildlife crossings

 

Did you know that there are now five wildlife underpasses under Tangerine Road?

As part of a larger project to improve Tangerine Road, five existing drainage structures were enhanced and improved to better accommodate safe wildlife movement across this popular roadway. This is a cost-effective way to increase connectivity across roadways that is less visible to the general public (as compared to a wildlife bridge) but still very important. Construction was completed on these wildlife underpasses in Spring 2018 with the cooperation of the Town of Marana, Pima County, the Regional Transportation Authority (RTA), Arizona Game and Fish Department (AGFD), the Coalition for Sonoran Desert Protection, and other members of the RTA’s Wildlife Linkages Sub-Committee.

Starting in 2010, the AGFD completed pre-construction monitoring using roadkill surveys. After the underpasses were completed in Spring 2018, the AGFD started a 3-year post-construction monitoring project, including roadkill surveys and monitoring wildlife use of the crossings using wildlife cameras. According to an April 2019 progress report from AGFD:

Between May and September 2010 5,152 road mortalities representing 88 species were documented, helping to identify hot spots for future implementation of fencing and wildlife crossing structures.

[Using this data], the objectives of this construction project were to:

  • Increase the size of five drainage structures and modify inlets/outlets to accommodate medium-sized mammals.
  • Add funnel fencing at the crossings.
  • Conduct habitat establishment evaluations, for three seasons, beginning one year after project completion, to determine whether any adaptive management measures are necessary to improve the effectiveness of the wildlife crossing structures.

Post-construction roadkill surveys began in Spring 2019. An April 2019 progress report primarily includes data from wildlife cameras installed on the underpasses and can be found HERE. A few data points and photos from the report are highlighted below:

Data has been analyzed to January 7th, 2019, this represents two full months of monitoring data for all five structures. A combined total of 1049 crossings by 17 wildlife species have been documented across all 5 structures to date. Coyote, javelina, and bobcat constitute the most commonly recorded species with 475, 365, and 130 crossings respectively, representing 93% of all documented crossings.

Mule deer and coyotes have both successfully crossed Tangerine Road safely using five new wildlife underpasses. These underpasses were created by enhancing existing drainage structures using voter-approved money from the Regional Transportation Authority’s wildlife linkages infrastructure funds. Photos courtesy Arizona Game and Fish Department.

 

This is exciting news for wildlife in the Tortolita Fan and motorists along Tangerine Road. With the inclusion of wildlife fencing on either side of these five underpasses, wildlife are now being funneled to cross Tangerine Road under the roadway, leading to increased safety for wildlife and motorists.** We will share new monitoring results from AGFD when they release their next progress report on this project sometime in the next year. 

Thank you for supporting connected wildlife linkages and wildlife habitat! 

**Some observant community members have noted that this wildlife fencing is shorter than the wildlife fencing along Oracle Road. Why is this? The Tangerine Road wildlife fencing was designed for the medium-sized mammals that are most likely to use these smaller culvert wildlife crossings. 

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