Posts Tagged ‘wildlife crossings’
By Jessica Moreno, Conservation Science Director
One of the best things about doing roadkill surveys is watching the sunrise. During the monsoons, the sun breaks across the eastern horizon and lights up the moisture laden air and morning cloud cover with light and throws the foothills into brilliant color. The sun feels hopeful and the day new. The second-best thing is knowing that every datapoint is helping us make things better.
The 20-mile stretch of Interstate-10 (I-10) between Vail and Benson, east of Tucson, Arizona, divides the regionally important Rincon-Santa Rita-Whetstone Mountains Wildlife Linkage. This wildlife pathway is one of only a few – somewhat safe – crossing points across I-10 found between Tucson and New Mexico, and it encompasses several protected areas and important waters, including Davidson Canyon and Cienega Creek, making it critically important for desert wildlife in the face of climate change.
This wildlife pathway is protected partially by federally protected lands including Saguaro National Park, Rincon Wilderness, and Las Cienegas National Conservation Area. Pima County has invested in securing additional conservation lands in this linkage as mitigation under the Multi-Species Conservation Plan (MSCP), including Bar V Ranch, Cienega Creek Natural Preserve, Rancho Agua Verde, and Colossal Cave Mountain Park, which are managed under the Cienega Creek Management Plan.
However, I-10 cuts through this area of wildlife movement, resulting in more wildlife-vehicle collisions for large animals such as black bear, mule deer, whitetail deer, javelina, coyote, and mountain lion, as well as smaller species like box turtles, opossum, Antelope jackrabbit, white-nose coati, raccoon, badger, and bobcat. It also serves as a potential movement area for jaguars and ocelots. Existing culverts and right of way fencing are not currently adequate at reducing wildlife-vehicle collisions or ensuring safe wildlife passage in this area. Future growth and increases in traffic volumes will only worsen the frequency of vehicle-wildlife collisions.
Since 2006, several qualitative assessments and reports have been produced that highlight the area’s importance for wildlife movement, but there has not been a study that has collected data to build a high accuracy model of wildlife movements and roadkill locations along this corridor. With the lack of such a product, nothing has been done on the ground to reduce wildlife-vehicle collisions and to improve safe wildlife passage by employing effective mitigation structures like winged highway fencing or wildlife overpasses. The Coalition for Sonoran Desert Protection, in conjunction with partners, is spearheading the effort to collect data to provide the information necessary to make this stretch of I-10 a safer passage for both wildlife and people in this important corridor.
In the spring of 2017, CSDP conducted comprehensive assessments and wildlife surveys of the nearly 80 existing concrete box culverts and metal plate pipe structures between milepost 277-302 (Houghton Road to SR90), with participants from several government, nonprofit, and community partners, including the Arizona Game and Fish Department, Cochise County, Pima County, Tucson Audubon Society, Sky Island Alliance, Defenders of Wildlife, and the Wildlands Network. Our results indicated that this wildlife linkage could be made safer for wildlife and motorists by 1) installing wildlife funnel-fencing to keep animals off the highway and to direct wildlife toward existing crossing points; 2) retrofitting and widening existing drainage culverts located in high volume areas; and 3) construction of an additional wildlife crossing between Cienega Creek and the railroad underpass near Empirita Rd Exit 292.
Roadkill surveys were part of the next phase of this effort: to gather data on roadkill hotspots, together with wildlife passage rates using wildlife cameras in the best existing culverts. We hope this data will inform State and County highway and wildlife officials on where to focus mitigation efforts to improve highway safety and minimize wildlife-vehicle collisions with site-specific wildlife funnel-fencing installation, existing culvert retrofits, and new wildlife crossing structures. Our results illustrate the need to implement changes and provides baseline information to evaluate the success of future mitigation measures.
Our Desert Roadies project began with a team of volunteers to help collect wildlife-vehicle mortality data on Interstate-10 between SR83 and SR90, east of Tucson. Desert Roadies volunteers worked in teams of 2-4 people, including myself, to conduct driving roadkill surveys. Observations were recorded by our notetaker with the GPS coordinates. Surveys were conducted in the morning, starting up to 30 minutes before sunrise, every week for 6 weeks during the monsoon season in 2019 and 2020, beginning in July, except when conditions were bad for visibility or driving such as rain, dust storms, or other low visibility weather. In addition to these formal roadkill surveys, we collected other data on iNaturalist.org from community members and personally investigated reports about black bear mortalities. We also requested ADOT records on reported animal-vehicle crashes in the study area. This data was analyzed separately.
Due to the onset of the Covid-19 pandemic in March 2020, carpooling with volunteers was no longer a safe option. So, we adapted as best we could by canceling the planned spring 2020 survey and having another monsoon season survey instead, which was conducted by myself and my family, Eddie Moreno (who is also a biologist experienced in roadkill surveys) and my two toddlers munching on donuts and “helping” look for animals from the backseat. This survey was done when the state was under curfew and lockdown, resulting in reduced traffic volumes. This likely was one reason for fewer observations of roadkill during this survey window.
Walking surveys are the ideal method for complete and accurate data. But safety concerns eliminated that option because we are using volunteer participation and this is a busy interstate highway with narrow right of ways. Therefore, the roadkill survey portion of this project was designed to be a broad-brush stroke only and we anticipated a small sample size. Recording categories of small, medium, large animals and/or by clade (reptile, bird, small/med/large mammal) are adequate for our purpose. Because of the project design, we have near zero detectability of small animals, and instead our target species are deer, bear, coyote, bobcat, gray fox, javelina, and those larger animals that the Arizona Department of Transportation consider most hazardous to drivers. The data will hopefully serve to provide a preliminary look at potential roadkill hotspot areas. For best accuracy 1) our GPS units had a one-button click to mark points quickly, 2) volunteers could also use maps and mileposts to confirm locations, 3) we analyzed the data in 1-mile segments, which better informs the fencing solution strategy and somewhat addresses imprecise location information, and 4) a staff biologist was always present to provide corroborating identification.
We completed two monsoon survey seasons for roadkill observations in 2019 and 2020, resulting in 78 data points of at least 14 different species. We were able to detect animals as small as a rock squirrel or cottontail rabbit. Skunks, raptors, and deer were not identified to specific species. All of our deer mortality observations (n=2) occurred between mileposts 296-297, near the Pima-Cochise County line. A hotspot of roadkill observations occurred between mileposts 291-295 (between Cienega Creek and Empirita Rd), in an area that coincides with a gap in available culverts and crossing points, and near several culvert locations between mileposts 283-287.
I-10 has been identified as a significant barrier to black bears in southern Arizona. In 2011, Todd Atwood et al published a study describing I-10 as a more significant barrier to functional gene flow for black bears than the U.S.-Mexico border, identifying I-10 as the dividing line between the Border subpopulation of black bears to the south, and the White Mountain subpopulation to the north. In our study area, these subpopulations meet and Romeo and Juliet romances unfold, ensuring healthy black bear populations in Arizona and in Mexico. For black bears, I-10 may be a barrier to gene flow as well as a “population sink” due to wildlife-vehicle deaths. This could pose a significant issue for the Border subpopulation, which additionally faces barriers to movement at the U.S.-Mexico border due to the construction of the border wall and other border-related infrastructure such as roads and lighting. Without safe passage both north of I-10 or south of the border, our southern Arizona black bears are at risk of genetic isolation and disappearing all together (what we call extirpation).
We have gathered four records of black bear mortalities in recent years, and three of these are verified with photos. These records indicate that the bears attempted to cross I-10 by following higher elevation ridgelines closely associated with the two largest underpass structures at Davidson Canyon and Cienega Creek. We also have animal track and camera trap data showing successful passage under I-10 at a few specific culverts. Most of our observations show bears moving south. April-May and August-September appear to be peak periods of activity for black bears in this area according to our data.
Black bears are just one example of the impact I-10 is having on native wildlife. In addition to large animals like bear, deer, and jaguar, smaller animals are at risk as well. Saguaro National Park has been monitoring a disturbing decline in “lost carnivores” over the last decade, including skunks, foxes, and badgers. Biologists are also concerned about the local disappearance of smaller range habitat specialist species affected by habitat fragmentation, including box turtles, Antelope jackrabbits, skunks, kit foxes, badgers, and white-nose coati. Increasing wildlife connectivity conditions for black bears and deer should allow struggling populations to repopulate from connected habitat areas and also benefit a wide array of other species.
With the data we’ve collected, we have solid evidence to back up the need for funding wildlife funnel fencing where it is most needed and make the case for new or improved wildlife crossings.
Read CSDP’s final project report to Arizona Game and Fish Department here.
(Please note: Photos of roadkill animals are included in the report)
Want to help?
Although collecting information on roadkill is not for the faint of heart, the data it provides is valuable. In the future, CSDP will be looking to continue our Desert Roadies program in more areas. In the meantime, folks can also document sightings of wildlife on roads in Pima County at https://www.inaturalist.org/projects/csdp-safe-passages.
This work was made possible thanks to the time, effort, and skill of the following volunteers: Matt Clark, Sami Hammer, Bruce Jacobsen, Ken Lamberton, Eduardo Moreno, D’angelo Padilla, Raynor VanDeven, Althea Weeks, and Daisy Weeks.
We also want to thank Scott Sprague, Jeff Gagnon and Brit Oleson of the Arizona Game and Fish Department, and give special thanks to our collaborating partners: Myles Traphagen with The Wildlands Network and Brian Powell with Pima County Natural Resources, Parks and Recreation.
This project was funded in part by the Arizona Game and Fish Department Heritage Fund.
In January 2022, a group of people from Arizona Game and Fish Department, Arizona Department of Transportation, the Tohono O’odham Nation, and the Coalition for Sonoran Desert Protection conducted a scouting field trip to finalize the locations of two new wildlife bridges on SR86 near Kitt Peak. These bridges will complement two existing wildlife underpasses built nearby in 2013-2014. During the trip, the attendees also visited the underpasses and associated wildlife fencing and were able to identify ongoing maintenance tasks so these underpasses continue providing a safe crossing location for wildlife for many years to come.
The SR86 wildlife bridges will be built to attract local bighorn sheep and other wildlife so they can safely cross between the Baboquivari Mountains to the south and mountain ranges to the north. The Regional Transportation Authority is funding these crossings, under a plan approved by voters in 2006 from $45 million allocated for wildlife linkage infrastructure projects.
Check out some photos of the field trip below.
Want to learn more about what’s happening around the Oracle Road wildlife crossings? Check out this recent presentation given by our Conservation Science Director Jessica Moreno:
You can also view a pdf of the presentation HERE.
by Jessica Moreno, Conservation Science Director
The last time I took a stroll down Big Wash, which runs along the west side of Oracle Road, the chill air pressed against my face mask but still managed to carry the smell of triangle leaf bursage and creosote. Gambel’s quail scurried away with their bustling chip-chip-chip alarm call. Dry for most of the year in that characteristic way our desert washes are, Big Wash has served as a connection for animals moving back and forth between the Cañada del Oro Wash and open space north of Rancho Vistoso. It has always been an important wildlife movement area, a key feature in a linkage connecting the Tortolita and Catalina mountains, and now, with two wildlife crossings in place and wildlife monitoring efforts nearing a decade milestone, we are learning more every day about the habits and movements of animals that often remain just out of sight.
Five year ago, when the wildlife bridge and underpass were built on SR77, the red ribbon was cut, the first critter crossed, and we celebrated. But the work wasn’t quite over. In addition to wildlife monitoring, Phase II of the project was to finish placing the last sections of wildlife funnel fencing. Wildlife fencing is an essential part of every successful wildlife crossing and is a vital component of this project to both effectively reduce wildlife-vehicle collisions and maintain a connected landscape for wildlife populations and gene flow. But a few jurisdictional issues and challenges to fencing placement threatened to hold up the whole project, so the decision was made to complete the difficult pieces after the crossing structures were done. Arizona Game and Fish Department’s roadkill surveys confirmed hotpots associated with these fencing gaps. It was a problem, but addressing it had to be done right.
One of these fencing gaps was on either side of the wildlife underpass, at the Rancho Vistoso neighborhood of Vista Mirabella. We placed wildlife cameras to monitor the gaps and reached out to the residents and the HOA to help solve the problem. The solution, made possible thanks to the leadership of the Town of Oro Valley and the wise suggestion of one of the residents, is an elegant one. And it may very well be the first of its kind for wildlife exclusion: wildlife fencing connected to the sound wall will close the gaps at the north and south ends of the neighborhood, while specially designed automatic gates will secure the neighborhood entrances.
This is a unique circumstance since these are public streets and the gates, which are designed like a gated community entrance, will open to any approaching vehicle. They are planned to remain open during high volume traffic hours and close at night. The Regional Transportation Authority is covering the cost out of remaining funds from the original crossing construction budget, including re-vegetation and projected maintenance, and Oro Valley is taking responsibility to maintain the gates into the future.
After four years of outreach and problem solving as a community, we hope that construction on this final piece of the puzzle will begin this summer. There are still details to figure out, but light is at the end of the tunnel and the end result, I think, is something everyone can be proud to have taken part in.
A big thanks to Coalition volunteers Pat and Henry Miller for their help in monitoring the fencing gaps and their overall involvement in this project! And thank you to the Regional Transportation Authority, Pima County, the Town of Oro Valley, and the Arizona Game and Fish Department for your shared persistence in this project.
More information about this project can be found in a Power Point presentation recently created by the RTA and the Town of Oro Valley.
Did you know that there are five wildlife underpasses that traverse Tangerine Road? These wildlife underpasses were finished in 2018 and the Arizona Game and Fish Department (AGFD) is now in the middle of a post-construction monitoring study of the crossings. In May 2020, AGFD released its latest monitoring progress report. We’re happy to report there were some very encouraging data and findings!
According to the AGFD report:
Data has been analyzed to April 7th, 2020. A combined total of 5,996 crossings by 23 wildlife species have been recorded across all 5 structures. Coyote, javelina, gambel’s quail, and bobcat constitute the most commonly recorded species with 3,002, 1,695, 482, and 403 crossings respectively, representing 93% of all documented crossings. Crossings of note include a gila monster at one underpass in April 2019, and a mountain lion at a different underpass in June 2019.
A total of 40 species have been detected across the five structures to date. The greatest diversity has been observed at underpass #2 where 29 species have been recorded. 16 species have been detected at underpass #1, which is the smallest monitored structure.
[Note: a species is “detected” when it is observed near the crossing structure. This is a different data point than documenting that a species successfully crossed through the structure.]
The full AGFD monitoring report can be found HERE.
Arizona Game and Fish Department (AGFD) just released the latest and greatest monitoring data from the Oracle Road wildlife overpass and underpass. This represents FOUR FULL YEARS of monitoring these wildlife crossings since construction finished in March 2016.
Some notable data and results include:
- 26 different species have been observed using the crossings, including 11 species at the overpass and 25 species at the underpass.
- Over 10,000 wildlife crossings have been documented by AGFD cameras – 10,843 to be exact. These crossings are fairly evenly split between both structures, with 5,490 crossings at the overpass and 5,353 at the underpass.
- Over 98% of the crossings are by four species: mule deer, javelina, bobcat, and coyote.
- Total crossings at each structure have increased year upon year since construction finished. This means each year more and more wildlife are using these wildlife crossings.
For more results, you can read the full monitoring report HERE.
To learn more about why these crossings were built, how they were funded, and more, head over to the following webpages:
- Oracle Road Wildlife Crossings Overview
- Wildlife Results: It Works!
- The Big Picture: Tucson-Tortolita-Santa Catalina Mountains Wildlife Linkage
- Oracle Road Wildlife Crossings: Frequently Asked Questions
The Oracle Road wildlife crossings were recently featured on TV station FOX10’s Drone Zone segment in Phoenix. Check out this 3+ minute segment to see some amazing drone footage of both the Oracle Road wildlife underpass and overpass, along with a great interview of our partner Jeff Gagnon with the Arizona Game and Fish Department (click on the image/link below to access the full TV segment).
Thanks to all of our supporters and volunteers for another year of successful wildlife camera monitoring in the Tucson Mountains and Oro Valley study areas! See an overview of our Tucson Mountain camera project results HERE and our Oro Valley camera project results HERE.
We have been monitoring wildlife with wildlife cameras in the northern portion of the Tucson Mountains and Avra Valley for four years. To date we’ve seen over 30 species across 23 camera sites, data which helps inform our I-11 work and knowledge about the Tucson-Tortolita Mountain Wildlife Linkage. Javelina have been photographed most frequently, and it is good to see these native seed dispersers out and about! Other notable results in the last year include more badgers, and bobcats with kittens in tow.
In Oro Valley, we have been monitoring east and west of the Oracle Road wildlife bridge and underpass for a total of seven years! We now have excellent comparative data pre- and post- construction of the crossings that were built in May 2016. With 62 species across 49 camera sites (and nearly 78,000 photos!), we are seeing lots of cottontails and quail that are plentiful prey for coyotes, bobcats, and gray foxes. We’ve seen white-nose coati and bighorn, and our resident female mountain lion has appeared again this year several times just west of the wildlife bridge.
We will post more detailed results as we finalize project reports and dive into the fun and useful information these cameras have in store!
“ARC Solutions and the Center for Large Landscape Conservation are delighted to announce the release of (Re)Connecting Wild: Restoring Safe Passage.
This film tells the remarkable story of the decade-long effort by the Nevada Department of Transportation (NDOT) and its partners to improve human safety by re-connecting an historic mule deer migration that crosses over both US-93 and I-80 in rural Elko County, Nevada. Faced with hundreds of motorist crashes involving deer along these two highways, NDOT analyzed carcass and collision data, along with mule deer movement data collected by the Nevada Department of Wildlife, to identify the highest risk areas for deer-vehicle conflicts.
This analysis revealed four priorities, including 10 Mile Summit and HD Summit along US-93, and Silver Zone Pass and Pequop Summit along I-80. Armed with these priorities, NDOT set about planning a series of multi-faceted projects that ultimately resulted in the construction of five new wildlife overpasses and four new wildlife underpasses, plus connective fencing, as well as the integration of four existing vehicular underpasses that today serve as multi-use structures for both motorists and wildlife. Avoiding typical bridge designs, NDOT employed innovative, wildlife-friendly construction methods to reduce costs and construction time while also maximizing wildlife usage and acceptance.
These methods are depicted in a special time-lapse segment, which allows viewers to virtually witness construction of the wildlife crossing structures along I-80. Ultimately, NDOT’s tireless efforts have achieved its primary goal of improving human safety and welfare – as evidenced by the more than 40,000 successful crossings by wildlife at the four priority sites – while at the same time restoring safe passage for migratory mule deer to more than 1.5 million acres of summer and winter habitat.”
The Arizona State Land Department and the Town of Marana have recently begun discussions about changes to the Tortolita Preserve. This 2,400 acre preserve was established in consultation, as required by the Endangered Species Act, with the U.S. Fish and Wildlife Service as mitigation for habitat disturbance and effects to listed species resulting from the construction of the Dove Mountain development.
On October 9, 2019, the Coalition submitted comments to the Town of Marana with our recommendations on how to move forward with the future of the Tortolita Preserve. We recommend that any changes ensure the connection of the preserve with nearby core preserve areas and planned future wildlife crossings.
The full text of our comments can be found HERE.
“Marana negotiating Tortolita Preserve’s future” – Tucson Local Media (October 16, 2019)
“Neighbors, conservationists closely monitor what’s next in Marana” – KOLD13 (October 18, 2019)
We’ll be updating this post as we learn more or there is additional news coverage on this issue.