National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Northern Elephant Seal (Mirounga angustirostris) Monitoring at Point Reyes National Seashore 2008–2009 Breeding Seasons Natural Resource Technical Report NPS/SFAN/NRTR—2012/649 ON THE COVER Bull elephant seal at South Beach, Point Reyes National Seashore Photograph by: Sarah Allen Northern Elephant Seal Monitoring (Mirounga angustirostris) at Point Reyes National Seashore 2008–2009 Breeding Seasons Natural Resource Technical Report NPS/SFAN/NRTR—2012/649 Sarah Allen, Sarah Codde1, Heather Jensen, Elizabeth Wheeler2, Ben Becker, Dave Press, and Dale Roberts1 Point Reyes National Seashore 1 Bear Valley Road Point Reyes Station, CA 94956 1San Francisco Bay Area Inventory and Monitoring Program Point Reyes National Seashore 1 Bear Valley Road Point Reyes Station, CA 94956 2The Marine Mammal Center Fort Cronkite 2000 Bunker Road Sausalito, California 94965 July 2012 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado publishes a range of reports that address natural resource topics of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Technical Report Series is used to disseminate results of scientific studies in the physical, biological, and social sciences for both the advancement of science and the achievement of the National Park Service mission. The series provides contributors with a forum for displaying comprehensive data that are often deleted from journals because of page limitations. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This report received peer review by individuals who were not directly involved in the collection, analysis, or reporting of the data, and whose background and expertise put them on par technically and scientifically with the authors of the information. Data in this report were collected and analyzed using methods based on established, peer-reviewed protocols and were analyzed and interpreted within the guidelines of the protocols. Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Government. This report is available from the San Francisco Bay Area Network Inventory and Monitoring website (http://science.nature.nps.gov/im/units/sfan) and the Natural Resource Publications Management website (http://www.nature.nps.gov/publications/nrpm/). Please cite this publication as: Allen, S., S. Codde, H. Jensen, E. Wheeler, B. Becker, D. Press, and D. Roberts. 2012. Northern elephant seal monitoring (Mirounga angustirostris) at Point Reyes National Seashore: 2008– 2009 breeding seasons. Natural Resource Technical Report NPS/SFAN/NRTR—2012/649. National Park Service, Fort Collins, Colorado. NPS 612/118228, December 2012 ii Contents Page Figures............................................................................................................................................. v Tables ............................................................................................................................................ vii Executive Summary ....................................................................................................................... ix Acknowledgments.......................................................................................................................... xi Introduction ..................................................................................................................................... 1 Methods........................................................................................................................................... 3 Study Site ................................................................................................................................. 3 Field Methods .......................................................................................................................... 4 Population and Productivity Surveys .................................................................................. 4 Survivorship and Site Fidelity ............................................................................................ 4 Analytical Methods .................................................................................................................. 5 Data Management ............................................................................................................... 5 Population Size ................................................................................................................... 5 Productivity ......................................................................................................................... 6 Survivorship and Site Fidelity ............................................................................................ 6 Results ............................................................................................................................................. 7 Population surveys ................................................................................................................... 7 Productivity .............................................................................................................................. 8 Survivorship and Site Fidelity ............................................................................................... 12 Tag Resighting ....................................................................................................................... 12 Discussion ..................................................................................................................................... 15 Population Size and Productivity........................................................................................... 15 Environmental Indicator ........................................................................................................ 16 iii Contents (continued) Page Tagging and Tag Resighting .................................................................................................. 18 Other Research ....................................................................................................................... 19 Operational Issues .................................................................................................................. 20 Safety ................................................................................................................................ 20 Personnel ........................................................................................................................... 20 Permits .............................................................................................................................. 20 Literature Cited ............................................................................................................................. 21 Appendix A ................................................................................................................................... 23 iv Figures Page Figure 1. Northern elephant seal breeding sites at Point Reyes National Seashore....................... 3 Figure 2. Marin Conservation Corps-Americorps member, Erin Flynn, surveying seals at Point Reyes Headland. Photograph by Heather Jensen. ..................................................... 4 Figure 3. The maximum number of adult females at Point Reyes and at each sub- colony by year. ................................................................................................................................ 8 Figure 4. Number of northern elephant seal cows, and pup and weaned pups combined at Point Reyes National Seashore during the 2008 breeding season by survey date. ................................................................................................................................... 11 Figure 5. Number of northern elephant seal cows, and pup and weaned pups combined at Point Reyes National Seashore during the 2009 breeding season by survey date. ................................................................................................................................... 11 Figure 6. (a) A large landslide occurred at DSB in 2006-7 and (b) created habitat for seals breeding in 2008 and 2009. Photographs by Sarah Allen. ................................................... 16 Figure 7. Three-month running mean of a CDAS/Reanalysis-derived Southern Oscillation Index (RSOI). Anomalies are departures from the 1979-1995 base period means and are normalized by the mean annual standard deviation (NOAA 2010). ..................... 17 Figure 8. A comparison of monthly rainfall at Point Reyes from the winter of 2005- 06 to 2009-10. Note large rainfall in January 2007-08 and February 2008-09 (NPS unpublished weather