U.S. Fish & Wildlife Service Status Assessment and Conservation Recommendations for the Caspian Tern in North America August 2002 Recommended Citation: Shuford, W. D., and D. P. Craig. 2002. Status Assessment and Conservation Recommendations for the Caspian Tern (Sterna Caspia) in North America. U.S. Department of the Interior, Fish and Wildlife Service, Portland, OR. Status Assessment and Conservation Recommendations for the Caspian Tern (Sterna Caspia) in North America W. David Shuford PRBO Conservation Science 4990 Shoreline Highway Stinson Beach, CA 94970 email: [email protected] and David P. Craig Department of Biology Willamette University 900 State Street Salem, OR 97301 email: [email protected] August 2002 TABLE OF CONTENTS Acknowledgments ............................................................................................................................. viii Summary............................................................................................................................................... 1 Taxonomy ............................................................................................................................................. 2 Legal and Conservation Status ............................................................................................................. 2 United States .......................................................................................................................... 2 Canada .................................................................................................................................. 2 Mexico .................................................................................................................................. 4 Central and South Americas .................................................................................................. 4 Description ........................................................................................................................................... 4 Geographic Distribution ....................................................................................................................... 4 Breeding ................................................................................................................................ 4 Migration ............................................................................................................................... 7 Winter .................................................................................................................................... 8 Pacific Coast .......................................................................................................................... 9 Atlantic, Gulf, and Caribbean Coasts .................................................................................... 9 Summer Nonbreeding .......................................................................................................... 10 Natural History ................................................................................................................................... 11 Breeding .............................................................................................................................. 11 Nests and Nest Spacing ....................................................................................................... 11 Reproductive Phenology ..................................................................................................... 11 Breeding Site Fidelity ..........................................................................................................12 Demography and Limiting Factors ...................................................................................... 13 Predators .............................................................................................................................. 14 Diet ...................................................................................................................................... 15 Migration ............................................................................................................................. 15 Habitat Requirements ......................................................................................................................... 16 Breeding Season .................................................................................................................. 16 Migration ............................................................................................................................. 17 Winter and Summer Nonbreeding Seasons ......................................................................... 17 Population Estimates and Trends........................................................................................................ 17 Estimates.............................................................................................................................. 17 Trends .................................................................................................................................. 19 Trends from Regional Surveys ............................................................................................ 19 Pacific Coast/Western (interior) Region ................................................................. 19 Central Canada ....................................................................................................... 25 Great Lakes ............................................................................................................. 26 Gulf Coast ............................................................................................................... 26 Atlantic Coast ......................................................................................................... 31 Breeding Bird Survey Trends .............................................................................................. 31 Christmas Bird Count Trends .............................................................................................. 31 Threats ............................................................................................................................................. 32 Overutilization ..................................................................................................................... 32 Adequacy of Existing Regulatory Mechanisms .................................................................. 32 Habitat Loss and Degradation ............................................................................................. 32 Disease and Predation.......................................................................................................... 34 U.S. Fish & Wildlife Service - Status Assessment and Conservation Recommendations for the Caspian Tern - August 2002 ii Pesticides and Other Contaminants ........................................................................................ 34 Human Disturbance ................................................................................................................ 35 Introduced Species.................................................................................................................. 36 Population Size and Isolation ................................................................................................. 36 Concentration Risk ................................................................................................................. 36 Monitoring Activities.......................................................................................................................... 37 Regional Surveys .................................................................................................................... 37 Breeding Bird Survey ............................................................................................................. 37 Christmas Bird Count ............................................................................................................. 38 Management Activities ....................................................................................................................... 38 Management Activities in the Columbia River Estuary ......................................................... 38 Habitat and Vegetation Management...................................................................................... 39 Artificial Nest Platforms......................................................................................................... 40 Social Attraction ..................................................................................................................... 41 Predator Management .............................................................................................................42 Minimizing Disturbance ......................................................................................................... 42 Outreach and Education...................................................................................................................... 43 Status Recommendations.................................................................................................................... 43 Conservation Recommendations ........................................................................................................ 44 Monitoring Recommendations ..............................................................................................