UC Irvine

Intense road development and urbanization have fragmented the natural landscapeacross coastal Southern California since the middle of the 20th century. As mitigation efforts, in 1992 the Natural Community Conservation Plan and Habitat Conservation Plans I and II (NCCP&HCP I and II) allocated reserves and non-reserve open spaces to connect these fragmented natural habitats and foster the coexistence of wildlife and people in Orange County. Here, I aim to evaluate the effectiveness of two established wildlife corridors (the Sand Canyon Wash Corridor and the Bonita Creek Corridor) in southern Orange County, linking two large reserve areas (Figure 1). I conducted camera trapping surveys by using 11 cameras placed along these two linkage corridors. Additionally, I obtained more photographic data at 10 different camera stations within the Irvine Ranch Water District (IRWD) San Joaquin Marsh & Wildlife Sanctuary. Then, I calculated Relative Abundance Index (RAI) values based on the photographic capture rates of key vertebrate species of concern for each location. I compared the current RAI values with values from a study by Lyren et al. (2008) to illustrate the changes over a decade at three subsets of locations. I also obtained wildlife-vehicle collision (WVC) data from 2005 to 2019 from the City of Irvine Local Animal Services. I found an average of two bobcat mortalities event per year occurred until 2015. After 2015, no bobcat detection or roadkill mortality is observed. Additionally, the number of coyote detections has increased by almost 700% over a decade at these locations. It is likely that this result reflects urban coyotes’ greater ability to function in a changing environment and (greater) resilience to anthropogenic effects. The long-term success of wildlife corridors requires understanding how the regional environment may influence species composition and potential use of these linkage elements reserve designs over extended periods.