Use of Artificial Den Structures by Endangered San Joaquin Kit Foxes
The goal of this project is to determine whether endangered San Joaquin kit foxes will use artificial den structures, and if so, whether they exhibit a preference among designs and materials. Specific questions that will be addressed include:
Will kit foxes use artificial den structures?
Do kit foxes exhibit any preferences among six different den designs?
Do kit foxes exhibit any preferences among four different tunnel designs or between two different chamber designs?
Need and Benefit
In the San Joaquin Valley of California, profound loss, degradation, and fragmentation of habitat has seriously impacted many fish and wildlife species to the point where many are now at risk of extinction. A considerable proportion of these habitat impacts are a direct result of or have been facilitated by water storage and delivery activities funded by Reclamation. In response to these impacts and in coordination with other agencies, Reclamation has been sponsoring a number of significant efforts in the San Joaquin Valley to restore fish and wildlife habitat, enhance conservation of natural resources, and facilitate recovery efforts for rare species. Some of these efforts are in response to mandated mitigation requirements imposed by consultations with other Federal agencies (e.g., U.S. Fish and Wildlife Service), and other efforts are proactive attempts to reduce further impacts and to enhance restoration efforts.
San Joaquin kit foxes are endemic to the San Joaquin Valley and are listed as federally Endangered and California Threatened, primarily due to the habitat impacts described above. Kit foxes occur on a number of Reclamation properties and exhibit some capacity to use canals as movement corridors. Kit foxes have been documented using the rights-of-way of several canals in the San Joaquin Valley, including establishing dens in the rights-of-way. Although use of canals by kit foxes is viewed as positive, there is some risk of damage to canals if kit foxes dig dens in inappropriate locations.
In fiscal year (FY) 2001, Reclamation provided a S&T grant to examine the efficacy of using artificial den structures to mitigate impacts and to enhance habitat for kit foxes. To date, 34 artificial dens have been installed in Bakersfield, California. Six different den designs are being tested, and four different materials (polyvinyl chloride [PVC], plastic, metal, cement) were used in constructing the dens. Use of the dens by kit foxes and other species is being monitored using track stations and automatic camera stations. Data collected will be used to identify cost-effective artificial den structures that encourage use by kit foxes. These structures then can be used to enhance habitats for kit foxes. Along canals, such structures can be strategically placed to minimize risk to facilities.
Additionally, encouraging use of canal rights-of-way by kit foxes may provide another benefit. In areas where ground squirrels burrows threaten to compromise canals, artificial dens can be used to attract kit foxes which prey on the squirrels.
This project has yielded very positive results and is entering its final year. Additional funding will ensure optimal data collection and also will facilitate the preparation of one or more scientific manuscripts that will be provided in addition to the final report we will prepare. The results of this project will be applied to resolving conservation conflicts associated with Reclamation activities and to proactively enhance habitat, thereby furthering conservation and recovery efforts for San Joaquin kit foxes. This will significantly aid in fulfilling mandated compliance requirements and also will aid in reducing regulatory obstacles to future Reclamation projects in the San Joaquin Valley.
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