(USGS Research Proposal) Permeability of Roads and Culverts to Movement of the San Bernardino Kangaroo Rat and other Small Mammal Species

Focus Area

Wildlife & Ecosystems


Natural Resources






Over 3 years

Research Idea Scope

Project Description: With culverts installed in numerous locations throughout southern California to allow for hydrological flow under roadways, they also provide the secondary function of vagile species connectivity to habitat fragmented by transportation corridors. While numerous studies have been performed on the subject of wildlife crossing structures and passage (Kintsch and Cramer [2011]; Bissonette and Cramer [2008]; Clevenger and Huijser [2011]; McCollister and van Manen [2010]; Meese et al. [2009]), few have assessed the viability of culvert utilization for smaller mammal species within this area. Study Objectives: 1) Determine permeability of roads and culverts to movement of federally endangered San Bernardino Kangaroo Rat (SBKR) and other small mammal species (SMS) 2) Determine effect of roadways (with and without culverts) on survivorship of SBKR and SMS (compared to non-roaded areas) 3) Determine if management action(s) can increase permeability of SBKR and SMS to culverts (and/or reduce road mortality). Such as action could take the form of adding temporary fencing to direct species into culverts and deter them from crossing roads or, depending upon crossing type, adding a structure or ledge to ensure utilization. 4) A Before and After Control-Impact Design (BACI) would be utilized 5) Results could be inferred to other arid shrubland small mammal species and communities 6) Results will allow transportation agencies to make more informed decisions regarding design and management of roads and culverts within these habitat types. Study Components: •A four-year study utilizing the BACI Design; 2 years before and 2 years after management action; (May have one year of acclimation after management action to make it a 5-year study); •Live-trapping and pit-tagging small mammals of at least 6 population sites minimum; •Three or more study sites would contain a culvert or designed road crossing; •Three control (non-roaded) sites. •Road crossings would be monitored by pit tag reader and/or IR cameras. •Road and culvert permeability will be measured by movements among trap locations •Culvert permeability measured by pit tag reader within culvert and IR cameras (we would use these data to estimate detection probability so that we can estimate the parameters of road vs. culvert permeability). •Management actions as stated above in (3) will depend upon particular site needs/hypotheses. References: Bissonette, J.A. and P.C. Cramer. 2008. NCHRP Report 615: Evaluation of the Use and Effectiveness of Wildlife Crossings. Transportation Research Board of the National Academies, Washington D.C. Clevenger, A.P. and M.P. Huijser. 2011. Wildlife Crossing Structure Handbook, Design and Evaluation in North America, Publication No. FHWA-CFL/TD-11-003. Department of Transportation, Federal Highway Administration, Washington D.C., USA. Kintsch, J. and P.C. Cramer. 2011. Permeability of Existing Structures for Terrestrial Wildlife: A Passage Assessment System. Research Report No. WA_RD- 777.1. Washing State Department of Transportation, Olympia, WA. McCollister, M.F. and F.T. van Manen. 2010. Effectiveness of Wildlife Underpasses and Fencing to Reduce Wildlife-Vehicle Collisions. Journal of Wildlife Management, 74(8):1722-1731 Meese, R., F. M. Shilling, and J. F. Quinn. 2009. Wildlife Crossings Guidance Manual, Information Center for the Environment, Department of Environmental Science and Policy, University of California, Davis, CA.

Urgency and Payoff

The distribution of this species is limited to three discreet alluvial fans and washes within the Southern California area. With much of the historic range developed, the continued build-out of transportation infrastructure further fragments habitat upon which the species depends for survival. Culverts are the most cost-effective mechanisms for fluvial and animal movement; however, it is unknown if this species utilizes these features to reach adjacent habitat. Should it be proven that SBKR and other small mammals utilize culverts, this will result in a significant cost savings to transportation projects.

Suggested By

John M. Taylor US Fish and Wildlife Service 760-322-2070

[email protected]