Camera monitoring in the Design Phase of a wildlife crossing project on California Highway 17 informs project design and underscores the value of the corridor for mountain lions

Morgan Robertson, California Department of Transportation
Nancy Siepel, Wildlife Connectivity Specialist, San Luis Obispo, California, USA.
(805) 674-7615

Tanya Diamond, Co-Principal and Wildlife Ecologist-GIS Analyst, Pathways for Wildlife, Los
Gatos, California, USA.
(408) 891-9833

Ahiga Snyder, Co-Principal and Wildlife Researcher, Pathways for Wildlife, Los Gatos,
California, USA.
(408) 230-3302

Topic Area
Sustainability and Resilience in Transportation Systems

The Santa Cruz Mountains are becoming increasingly isolated by habitat fragmentation, making it more difficult for wildlife to traverse and occupy the mountain range. California Highway 17 connects the City of Santa Cruz in Santa Cruz County and the City of Los Gatos in Santa Clara County. Dense traffic, concrete median barriers, and a lack of adequate culvert or bridge under crossings create one of the most insurmountable obstacles to wildlife movement in the region.

In 2013 the California Department of Transportation (Caltrans) District 5 teamed up with the Land Trust of Santa Cruz County (LTSCC), Pathways for Wildlife, the University of California Santa Cruz Puma Study, the California Department of Fish and Wildlife, and the Santa Cruz County Regional Transportation Commission (SCCRTC) to develop workable solutions. Using GPS/radio telemetry provided by the Puma Study, camera trap data provided by Pathways for Wildlife, and roadkill data provided by Caltrans and Pathways for Wildlife, the team identified the highway curve at Laurel Road as the location for an undercrossing that would provide the greatest benefit. At the landscape level, several regional conservation plans have identified the Highway 17 Corridor as a critical linkage in connecting the Santa Cruz Mountains with the Diablo Mountain Range to the east and the Gabilan Range to the south.

In 2016 Caltrans District 5 secured funding for the environmental approval process and project design. Concurrently, the SCCRTC-marked five million dollars for construction through a transportation tax measure. In addition, the LTSCC was able to purchase 463 acres --- securing land in the wildlife corridor on both sides of the highway curve at Laurel Road. The preferred design for the wildlife undercrossing-an open span bridge with a natural bottom-- was presented in a public meeting in May 2018, receiving high levels of local support. Construction of the wildlife undercrossing is planned to begin in 2021.

During the project design phase, the LTSCC funded additional camera monitoring by Pathways for Wildlife on the properties adjacent to Highway 17. The camera data reflects a high diversity and abundance of native wildlife species using the LTSCC properties including several mountain lions, the target species for the undercrossing. In 2019, female mountain lions with young were recorded for the first time, using both sides of the highway, indicating the project area is important not only as a travel corridor but also for breeding and rearing young. In addition to underscoring the importance of these areas for pumas and other native species, the camera monitoring is providing information about local animal movement patterns that will help inform placement of landscape planting and game trails leading to the crossing. The data will also inform wildlife fencing placement, including potential locations for escape ramps, that will be included as part of the wildlife undercrossing project.

Abstract Keywords
wildlife crossing camera monitoring