Illuminating the Covert Biodiversity of Organ Pipe Cactus National Monument

The Sonoran Desert is one of the most biodiverse deserts in North America. Many of its desert-dwelling species are threatened by habitat degradation from roadways. In addition, habitat connectivity for many species is disrupted by a major highway in Organ Pipe Cactus National Monument (OPCNM), a UNESCO International Biosphere Reserve in the heart of the Sonoran Desert. Although previous research has begun to investigate how wildlife use human-made structures, such as drainage culverts, to cross under roadways in other regions, this information is lacking for this region. To fill the knowledge gap regarding how wildlife use the culverts under a major highway in OPCNM, I examined temporal, environmental, and physical culvert attributes that may facilitate wildlife use by using game cameras to capture photos of taxa using the culverts. I found that wildlife mainly used the culverts at night and were most found to be walking in the culverts, although I also documented resource acquisition such as drinking and predation. I also examined characteristics that influence Sonoran desert tortoise habitat occupancy. I found that Sonoran desert tortoise, a Species of Greatest Conservation Need in Arizona, was more likely to occupy habitats with sloped topography with a high percentage of vegetation cover. These findings suggest that sloped topography and vegetation cover provide habitat resources that support Sonoran desert tortoise persistence in OPCNM, thus warranting protection to maintain habitat for this imperiled species. The findings of this thesis indicate that continued monitoring of species’ responses to certain habitat attributes is warranted and therefore it is important to consider those attributes when implementing management strategies.