Use of off-highway vehicles (OHVs; defined as any type of motorized vehicle designed primarily for travel over unpaved roads and trailsas well as across roadless areas)is a rapidly increasing form of outdoor recreation. In Arizona, Department of Transportation records indicate a 359%increase in the number of titled OHVs during 1998-2008.While the Arizona Game and Fish Department (AZGFD) recognizesOHV users as an important recreational user group, the agency must consider the multiple potential impacts of OHV activity. Current scientific literature establishes that OHV recreation can have a wide range of negative ecological effects and that these effects may be especially acute in the ecologically sensitive deserts of the U.S. Southwest. AZGFD recognizes the need to provide OHV recreational opportunitieswhile maintaining the health and productivity of native habitats and wildlife. To find this balance the department seeks to better understand the potential impacts of OHV use in Arizona.
The two study locations were selected because they offer habitat typical to the kit foxes in Arizona. The first site is located adjacent to the southern Maricopa Mountains, at the southern end of the Sonoran Desert National Monument, whereas the second is located on Arizona State Trust lands in the Desert Wells Multiuse Area east of Apache Junction. Both areas are approximately78 km2 (30 mi2 ) in size and are within the Sonoran Desert scrub biome generally characterized by two plant communities: the creosote bush-white bursage (Larreatridentata-Ambrosia dumosa) series of the Lower Colorado River Valley subdivision and the paloverde (Cercidiummicrophyllum)-cacti-mixed scrub series of the Arizona Upland subdivision. The lower bajadas, flats, and desert wash areas are dominated by creosote-bursage vegetation, while higher elevations and the more rugged mountainous terrain are dominated by paloverde-mixed-cacti and shrub communities, including paloverde, cholla (Opuntia spp.), and mesquite (Prosopisvelutinus).The study focuses on relatively flat areas at elevations of 244 - 488 meters (800 – 1,600 ft).
Objectives and Approach
To address the need for information regarding the effects of OHV use, AZGFD is initiating a project to examine the potential impacts of OHV use on kit foxes (Vulpesmacrotis) in the Sonoran Desert. Kit foxes were selected for this study because they are potentially impacted directly and indirectly by OHV use through direct mortality, disturbance, impacts to den sites, and direct and indirect influence on their prey base.Additionally, few studies have been done on kit foxes in the SonoranDesert environment and little information exists regarding the status of kit foxes in Arizona.
Our specific objectives for the project are to determine if kit fox habitat selection is influenced by OHV use and whether kit foxes exhibit a shift in space use in response to temporal changes in level of OHV use. We are studying kit foxes in two study areas, each of which isused for OHV activity but also includes areas with little or no OHV use. To address our first objective, we will monitor 12 kit foxes fitted with Global Positioning System (GPS) collars for two years. We will use GPS-collar data to evaluate habitat selection, with an index of OHV use included as one covariate in a multivariate analysis. Other covariates will include vegetative type, indices of predator presence and prey availability, topography, livestock presence and water availability. We will also use GPS data to address our second objective by comparing space use of collared foxes during periods of relatively low OHV use (weekdays and non-holidays) with space use during periods of relatively higher OHV use (weekends and holidays). During the second year of the study, we will use an experimental approach to evaluate the influence of increased levels of OHV use on kit fox space use and habitat selection, by temporarily increasing OHV activity in selected portions of the study area and continuing data collection and analysis of habitat selection and space use. We will use this experimental approach to further address our two objectives by testing whether increased levels of OHV use influence kit fox space use or habitat selection.
The primary purpose of this study is to better understand the effects of OHV recreation on wildlife in Arizona’s desert habitats. Datafrom this project can be used to inform decisions concerning management of areas preferable to OHV recreation and how to manage for diverse outdoor recreational opportunities while protecting Arizona’s native species and habitats.
For More Information Contact:
Andrew Jones, Wildlife Specialist
Arizona Game and Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086-5000 E-Mail: AJones@azgfd.gov