Background/Question/Methods The response of different vertebrates to urbanization has been surprising. Changes in structure, water availability, predator and prey communities and connectivity provide opportunities for some taxa while limiting the success of others. The few studies of urban bats indicate that diverse communities of bats persist in these modified environments, however, no comprehensive study of the bat fauna has been done for the city of San Francisco, California. I surveyed 21 natural areas in parks across the city using Pettersson D240X acoustic monitoring equipment to estimate species richness and relative foraging activity on a quarterly basis beginning in late Spring 2008. Results/Conclusions Preliminary results show at least three species are present and active year-round, in contrast to an earlier study with six species and more seasonal variation. There was a positive correlation between presence of lakes and perennial streams in parks and both species richness and relative foraging activity. Tadarida brasiliensis is widespread and abundant, and Myotis yumanensis and Lasiurus blossevillii are restricted to parks with lakes.