Nest Predation Risk in Suburban versus Grassland Edges Associated with Adjacent Coastal Sage Scrub Interiors

California is a biodiversity hotspot with multiple endemic species threatened by human impacts including urbanization. Suburban developments and edges where habitat types meet possess predators in greater abundance and diversity than interior portions of natural habitat. Thus, edges created by suburban developments may be particularly risky. We studied artificial nest predation along edges where suburban and grassland habitats were adjacent to Coastal Sage Scrub (CSS) habitat at Starr Ranch Audubon Sanctuary, Orange County, California. We hypothesized that nest depredation would be higher near edges than in CSS interior and that near suburb treatments would have higher nest predation than treatments near natural habitat. We placed 24 nests with a quail egg and a clay egg in shrubs (N=12) or on the ground (N=12) in each of four treatments (near suburb: edge and CSS interior; natural: grassland-CSS edge, CSS interior). Nest depredation was measured at 52 and 120 hours. We surveyed each treatment to quantify avian predators, vegetation type and cover. Contrary to our prediction, there was no significant difference in nest depredation near edges compared to CSS interiors. However, the near suburb treatments had higher nest predation than the natural treatments. High percent grass cover and open-ground was correlated with lower nest predation. There was no significant difference in predation of nests on the ground versus in shrubs. We found no significant difference in the presence of avian nest predators across treatments. Managing habitat near suburban developments to make them similar to natural habitat may reduce nest predation risk.