Wildlife Results: It Works!

Since the Oracle Road wildlife crossing were finished in March 2016, the Arizona Game and Fish Department has been monitoring the crossings for wildlife use and conducting regular roadkill surveys along this stretch of Oracle Road. 

The most recent report from Arizona Game and Fish Department’s monitoring results can be found HERE.

The first to cross: a desert tortoise interrupted construction workers to use the wildlife underpass – before construction was even complete. Photo courtesy Jesse Espinoza and Granite Construction (2015).

BACKGROUND

Now that the Oracle Road wildlife crossings are finished, a 4-year monitoring program is underway to document all the wildlife using these crossings. Arizona Game and Fish Department (AGFD) is spearheading the program, with collaboration from the Coalition and our volunteer-driven Wildlife Camera Monitoring Program. 

In April 2016, the AGFD installed 8 video cameras and 4 still cameras (all motion-activated) on the new Oracle Road wildlife bridge. They also installed 4 still cameras on the wildlife underpass. AGFD will also be conducting roadkill surveys, monitoring the movements of Sonoran Desert tortoises and mule deer in the area of the crossings, and providing recommendations for the adaptive management of the structures.

MONITORING RESULTS

According to the March 2019 monitoring report from AGFD:

Image data has been analyzed from project inception (April 18th, 2016) to January 7th, 2019. A total of 24 native vertebrate species have been documented at the crossing structures, nine at the overpass, and 23 at the underpass. 13 of these species have been documented crossing SR77 at the structures, nine at the overpass, and 12 at the underpass. 5999 wildlife crossings have been documented across both structures, with 3187 and 2812 at the overpass and underpass respectively. Mule deer, coyote, and javelina utilize the overpass most regularly with 2528, 378, and 228 crossings respectively. At the underpass javelina, coyote, and mule deer are again the most regularly documented species with 1501, 794, and 299 crossings respectively. One species of particular note has been documented crossing through the underpass, that being the white-nosed coati (Nasua narica) represented by a single record from September 2017.

Road mortality surveys were completed in August 2018, 14 survey cycles have been completed in total, 7 each in 2017 and 2018 respectively. Each year four survey cycles were completed during the first four weeks of May; the remaining three survey cycles were completed during the first three weeks of August. All collected road mortality data has been compiled. 1,849 observations were recorded over the course of the project, of these 1,799 related to vertebrate mortalities, representing at least 80 species. Merriam’s kangaroo rat, couch’s spadefoot, and regal horned lizard were the most commonly recorded species with 257, 187, and 143 records respectively. Notable records include; Sonoran desert tortoise, gila monster, bobcat, javelina, black-necked gartersnake, checkered gartersnake, barn owl, and kit fox.

The status of installed wildlife fencing along the surveyed extent of SR77 allows us to compare the effectiveness of wildlife fencing in several configurations with respect to the ROW. There is evidence to suggest that installed wildlife fencing is proving effective throughout the surveyed extent. A single ungulate mortality has been recorded and very few carnivores were detected within the ROW. Overall, vertebrate mortality hotspots were most significant where ROW 17 fencing directly fronted the highway on one side but was retracted or absent on the opposing side. This was most pronounced between mile markers 82 and 83 where land adjacent to the unfenced frontage is less developed. Equally, the most significant vertebrate mortality cold spots were detected where development adjacent to the ROW was heavier and/or where ROW fencing was in situ along both frontages.

The installed wildlife fencing is designed to exclude all but wildlife except for birds and climbing rodents. Wildlife fencing currently exists on BOTH sides of Oracle Road between mileposts 84 and 86, but only on the EAST side of the road between mileposts 82 and 84, which is likely why we are seeing a roadkill hotspot appearing there. We are working with our partners and nearby homeowners to close these gaps in the wildlife fence. 

 

This graph shows the total wildlife crossings at both the Oracle Road underpass and overpass from April 2016-December 2018.

 

This graph shows the total mule deer crossings at both the Oracle Road underpass and overpass from April 2016-December 2018. Mule deer started using the overpass immediately after construction concluded. They took longer to acclimate to the underpass; however, after ~2 years they started using the underpass more regularly in winter 2018.

 

This table shows the variety of wildlife species that have either been detected near the Oracle Road wildlife crossings or confirmed as crossing them. Click on the image to make it larger.

 

This table shows the exact number of detected crossings of the most common species to use the Oracle Road wildlife crossings through January 7, 2019. Click on the image to make it larger.

 

AGFD’s complete 4-year monitoring plan can be found here. If you are interested in more data, maps, tables, and photos of wildlife using the Oracle Road wildlife crossings, please check out the latest monitoring report HERE. Also, scroll to the second half of this AGFD PowerPoint Presentation to see even more data. 

Articles in the News & Updates section of our website with more information about monitoring results from the Oracle Road wildlife crossings can be found below:

The latest and greatest results from the Oracle Road wildlife crossings – July 19, 2019

New interactive case study about the Oracle Road wildlife crossings – December 7, 2018

New Game and Fish monitoring report documents over 4,400 animals using Oracle Road wildlife crossings in first 2 years – October 4, 2018

In the News: Oracle Road wildlife crossing results make a splash! – March 16, 2017

The first year of results are in! – March 13, 2017

New video shows deer and other animals crossing Oracle Road wildlife bridge – April 19, 2016

 

Video footage of animals using the wildlife bridge. All video footage and still photos courtesy Arizona Game and Fish Department.

Still photos of wildlife using both the wildlife bridge and wildlife underpass

A herd of deer crosses the Oracle Road wildlife bridge in April 2016.

Picture 1 of 13

A mule deer exits the west entrance of the Oracle Road wildlife underpass in April 2016.

Picture 1 of 14

 

WILDLIFE CAMERA MONITORING PROJECT

The Coalition’s own wildlife camera monitoring project will supplement these studies, by revealing the number and type of species that are moving in the area that could potentially use the wildlife crossings. For instance, our cameras captured one photograph of a white-nose coati approaching the underpass from the east, but AGFD’s cameras did not record it using the underpass. This information is useful to help biologists determine if any changes or modifications should be made to improve the effectiveness of the structures for certain species.

Learn more about our camera monitoring project, and see the photos, HERE.

HELP US GATHER MORE DATA!

We need your eyes, too. Please report wildlife sightings on Oracle Road (alive or dead), and in the surrounding area in Rancho Vistoso, Sun City, and other nearby neighborhoods, bike paths, and trails. Share what you see on: http://www.inaturalist.org/projects/csdp-safe-passages