Bat communities of Rancho Jamul Ecological Reserve and Santa Ysabel Open Space Preserve before and after the 2003 wildfires. Data Summary Prepared for: San Diego Association of Governments U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY WESTERN ECOLOGICAL RESEARCH CENTER Bat communities of Rancho Jamul Ecological Reserve and Santa Ysabel Open Space Preserve before and after the 2003 wildfires. By: Carlton J. Rochester1, Adam R. Backlin2, Drew C. Stokes 3, Milan J. Mitrovich2, Cheryl S. Brehme1, and Robert N. Fisher1 U.S. GEOLOGICAL SURVEY WESTERN ECOLOGICAL RESEARCH CENTER Data Summary Prepared for: San Diego Association of Governments 1San Diego Field Station – San Diego Office USGS Western Ecological Research Center 4165 Spruance Road, Suite 200 San Diego, CA 92101 2San Diego Field Station – Irvine Office USGS Western Ecological Research Center 320 Commerce Drive, Suite 150 Irvine, CA 92602 3San Diego Natural History Museum Department of Birds and Mammals 1788 El Prado San Diego, CA 92101 Sacramento, California 2010 ii U.S. DEPARTMENT OF THE INTERIOR KEN SALAZAR, SECRETARY U.S. GEOLOGICAL SURVEY Marcia McNutt, Director Suggested citation: Rochester, C. J., A. R. Backlin, D. C. Stokes, M. J. Mitrovich, C. S. Brehme, and R. N. Fisher. 2010. Bat communities of Rancho Jamul Ecological Reserve and Santa Ysabel Open Space Preserve before and after the 2003 wildfires. U.S. Geological Survey-Data Summary prepared for San Diego Association of Governments. 57 pp. The use of firm, trade, or brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. For additional information, contact: Center Director U.S. Geological Survey Western Ecological Research Center 3020 State University Drive East Modoc Hall, Room 3006 Sacramento, CA 95819 iii Table of Contents Abstract................................................................................................................................1 1. Introduction.....................................................................................................................2 2. Study Area .....................................................................................................................3 3. Materials and Methods....................................................................................................4 3.1 Field Methods .........................................................................................................4 3.1.1 Foraging Bat Surveys..................................................................................4 3.1.2 Roost Surveys .............................................................................................6 3.2 Statistical Analysis..................................................................................................7 4. Results and Discussion ...................................................................................................8 4.1 Foraging Bat Surveys..............................................................................................9 4.1.1 Active Anabat Surveys ...............................................................................9 4.1.2 Passive Anabat Surveys ............................................................................10 4.1.3 Mist-Net Surveys ......................................................................................10 4.1.4 Audible Surveys........................................................................................10 4.1.5 Visual Surveys ..........................................................................................11 4.2 Roost Surveys ........................................................................................................11 4.3 Statistical Results...................................................................................................11 5. Conclusions...................................................................................................................14 6. Acknowledgements.......................................................................................................14 7. Literature Cited .............................................................................................................15 Appendix 1. Examples of bat calls from reference library ...............................................35 Appendix 2. Species accounts...........................................................................................36 Pallid bat ......................................................................................................................36 Townsend’s big-eared bat............................................................................................36 Big brown bat...............................................................................................................37 Western mastiff bat......................................................................................................38 Western red bat ............................................................................................................38 Hoary bat......................................................................................................................39 Western yellow bat ......................................................................................................40 California myotis .........................................................................................................40 Western small-footed bat .............................................................................................41 Long-eared bat .............................................................................................................42 Yuma bat......................................................................................................................42 Pocketed free-tailed bat................................................................................................43 Big free-tailed bat ........................................................................................................44 Western pipistrelle .......................................................................................................44 Mexican free-tailed bat ................................................................................................45 Appendix 3. Alternate tables and figures for public release.............................................46 Table 1. Survey sites...................................................................................................47 Figure 2. Survey sites at Rancho Jamal Ecological Reserve ......................................48 Figure 3. Survey sites at Santa Ysabel Open Space Preserve.....................................49 Appendix 4. Sample data ..................................................................................................50 iv Tables Table 1. Survey sites.........................................................................................................18 Table 2. Anabat survey efforts at Rancho Jamul Ecological Reserve ..............................19 Table 3. Anabat survey efforts at Santa Ysabel Open Space Preserve.............................20 Table 4. Active-Anabat survey results..............................................................................21 Table 5. Passive-Anabat survey results ............................................................................23 Table 6. Mist-net survey results........................................................................................25 Table 7. Audible and Roost survey results .......................................................................27 Table 8. Species detection rates........................................................................................28 Figures Figure 1. Study area ..........................................................................................................29 Figure 2. Survey sites at Rancho Jamal Ecological Reserve ............................................30 Figure 3. Survey sites at Santa Ysabel Open Space Preserve...........................................31 Figure 4. Study area differences: Multidimensional scaling plot .....................................32 Figure 5. Differences in time period: Multidimensional scaling plot...............................33 Figure 6. Differences in fire condition: Multidimensional scaling plot............................34 v ABSTRACT We investigated the role of large-scale wildfires on the community composition and structure of foraging bats within San Diego County, California. In October and November of 2003, large–scale wildfires burned nearly 130,000 hectares of San Diego County. To assess the potential impacts of these fires on the native bat communities, we conducted surveys at eleven sites within each of our two study areas, Rancho Jamul Ecological Reserve - Hollenbeck Canyon Wildlife Area and Santa Ysabel Open Space Preserve. At each study area a subset of these sites was sampled before the fires (2001- 2003) and a subset after the fires (2005-2006). Our pre-fire sampling efforts included five survey techniques: active-Anabat, mist-netting, roost, visual, and audible. These same five techniques were employed during the first year of post-fire sampling, 2005. In 2006, we altered our survey methods by discontinuing mist-netting and began using passive-Anabat monitoring stations instead of an actively monitored station. In total, we detected 15 bat