Watch all our progress videos for Habitat Restoration Day on our YouTube Channel!
In August 2023, with funding from the Santa Cruz Valley National Heritage Area, we launched a project to maintain and revegetate the Oracle Road wildlife crossing structures for the first time since their construction in 2016. This project set out to remove invasive species from the wildlife crossings; enhance wildlife habitat on these wildlife crossings with additional native plants and seed mixes; and provide public education and outreach through a series of 12 volunteer workdays, educational videos, and permanent interpretive and informational signage. Carianne Funicelli from Strategic Habitat Enhancements partnered with us closely on this project, bringing restoration supplies and instructing volunteers on how to plant trees and shrubs, how to spread the seed mix, how to propagate cacti, and how to cage and water plants. Here is a summary of our “Habitat Restoration Days” over the past year!
On the first project day, our mission was to scout the wildlife crossing bridge for invasive plant species and begin removing them. We discovered invasive and non-native species such as buffelgrass, Layman’s love grass, tick-grass and Russian thistle. However, our largest priority was to remove buffelgrass patches because it was not only the most prevalent invasive species, but it is also the most dangerous for our crossing structures.
Buffelgrass (Cenchrus ciliaris), in addition to decreasing available space for native plants to grow and diversify this habitat, is a serious fire hazard. This invasive grass is adapted to fire and can burn at and survive at temperatures of 1300-1400⁰ F! The Sonoran Desert has not evolved resilience to these extreme fires and will have a hard time recovering from the damage, if at all. Meanwhile, as the native vegetation struggles to re-establish, buffelgrass will continue to thrive and suffocate the landscape.
With this in mind, on the second Habitat Restoration Day in October, our focus was to knock out the buffelgrass and other invasive species at both wildlife crossings structures, the wildlife bridge on Oracle Road and the underpass. We split our volunteers into two teams, one for each wildlife crossing structure. In addition to buffelgrass treatment, the team that was placed at the wildlife bridge planted several native trees, including paloverdes, mesquites and ironwoods.
It was hard work, but together, the Desert Wildlife Crossing Crew managed to remove 48 bags of buffelgrass from the crossing structures!
On our third Habitat Restoration Day, more trees were planted and watered and a native seed mix was spread on the bridge. This seed mix contains native shrub and grass seeds.
While working on the wildlife bridge in November, we also encountered a very special visitor! This was the first recording of a Sonoran Desert tortoise using our wildlife crossing bridge. It’s incredibly rewarding to watch our efforts make a difference in the lives of wildlife. (You can read the full story of the significance of this encounter in this blog post!)
On December 2nd, our focus was to plant shrubs at both wildlife crossing structures and continue invasive species removal. We planted 15 shrubs, including five graythorns and 10 triangleleaf bursages. In addition to planting, we spread native seeds at the underpass, focusing some seeds on a slope that is beginning to erode. Our hope is that these plants will help secure the soil and aid in erosion control. We further improved the underpass habitat by doing some pruning of large shrubs growing in the entrance of the underpass. When passing through a tunnel, mule deer feel more comfortable when they can see the other side, so pruning back some vegetation will help more deer use this crossing structure.
January, February and March were plant focused days! We planted lots of vegetation on the wildlife bridge- including soaptree yuccas, and ocotillos. In February, we planted 20 globe mallows and 20 Parry penstemon plants. In March, we came back to find most of these baby plants were in good health and the Desert Wildlife Crossing Crew made sure to water each little plant. The soft soil from the recent rains made removing invasive plants a breeze- we discovered a hidden patch and removed 7 more bags of buffelgrass during these months!
Spring at the wildlife crossings was a sight to behold. Annual flowers, including some seeds from the seed mixes had sprouted and the crossings were full of color. Lupines, desert marigolds, brittlebush and globemallow carpeted the bridge and underpass. Many of the shrubs we planted flowered as well, seeding new generations of plants!
We noticed pretty quickly that the wildlife appreciated these new plants – maybe a little too much. The globe mallows were starting to get eaten, likely by rabbits. In April, we installed small wire cages to protect our plants while they were still getting established. Once these plants are big enough to act as cover and a food source, we’ll remove the cages.
April marked another exciting addition to the crossings – new permanent signage! These signs will remind visitors to be mindful of their impact on wildlife and provide resources to learn more about our work on the Oracle Road wildlife crossings and about wildlife crossings in southern Arizona.
In May, Carianne led a workshop with volunteers showing how to properly and safely collect cactus cuttings and how to propagate them on the wildlife crossing bridge. We strategically placed these cactus cuttings on the bridge to provide cover for smaller animals, such as rodents and lizards, as they are crossing the bridge.
As it started warming up, our next priority was to thoroughly water all our plants. We’ve been intermittently watering, but the next few project days, in June and July, were dedicated to watering plants and scouting for any invasive plants we may have missed. Lo and behold a new invasive started to pop up – Russian thistle. Russian thistle is an invasive and non-native plant that is very spikey and can grow very large. It is not as much as a fire hazard as buffelgrass, but it’s best to remove it as soon as possible, before it smothers the area and becomes unmanageably thorny. As invasive species management goes, it’s an ongoing and reoccurring process. We plan on continuing our invasive species treatment into the future to maintain the ecological health of the crossings.
For our last official project day, and as a last hurrah, we invited Bat Conservation International to the bridge to partner with us and help us plant 50 agaves on the wildlife bridge! These agaves are the pollinator plants of native bats, and we hope that this installation will attract them to the bridge and increase the plant and animal diversity of the bridge habitat. We appreciate the huge turn-out for this event – we had a lot to do, and the many hands made light work!
As a finishing touch to this project, we installed interpretive signage near the Big Wash trailhead. This trail passes by the Oracle Road underpass, and gives information about its history, its significance in this area, as well as links to learn more about our work for wildlife. We hope that you stop by this new sign next time you’re in the area for a hike!
We are so proud of how far the habitat has come on the Oracle Road wildlife crossings. Check out how the habitat compares to when it was first constructed in 2016! The habitat blends into the landscape and looks much more natural. We are in the process of analyzing our wildlife camera data in the area to determine the impact this restoration work has had on the species diversity on the crossings. Stay tuned for this report and other updates about our work on these wildlife crossings and others into the future!
To all the volunteers that joined us for this project – THANK YOU! Your time, effort and dedication has been invaluable to us.
A huge thank you to Carianne at Strategic Habitat Enhancements for providing all the plants, tools, caging, seed mixes, and native plant expertise that make this project possible!
Thank you to Bat Conservation International for partnering with us and helping us plant agaves to the wildlife bridge!
To the Santa Cruz Valley National Heritage Area – THANK YOU for funding this project and providing the resources we needed to make our Habitat Restoration Days a success.
