Thesis

The Effect of Interstate 15 on Mammalian Communities in Southern California's Conserved Lands

Human induced fragmentation of habitat through urbanization and road construction blocks routes of immigration and emigration for wildlife and can interrupt metapopulation dynamics, leading to localized extinction events. To determine the effect of the I-15 highway on the mammalian mesopredator community composition in a protected wildlife corridor, the Santa Ana Palomar Mountains Linkage (SAPML), 32 camera stations (e.g. camera traps) were placed at varying distances from the road from 2012-2013. Cameras were also placed at the entrances to culverts that run under the I-15 in an attempt to capture mammals that may pass under the road. Out of 1043 sampling days, 765 video clips were captured of which 232 recorded positive detections of the focal species. While distance from road and noise pollution from traffic were predicted to have the greatest effects on mammalian community composition, habitat type was found to be the strongest predictor of detection of bobcat (Lynx rufus), coyote (Canis latrans), and gray fox (Urocyon cinereoargenteus). There were an insufficient number of video clips recorded of mammalian wildlife using the culverts, limiting the ability to conduct a rigorous statistical analysis on the effectiveness of culverts as wildlife passages in the SAPML. However, anecdotal evidence suggests that at least some individuals of coyote, bobcat, gray fox, and raccoon (Procyon lotor) are successfully moving through these culverts.

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