Inland-breeding Pelicans, Cormorants, Gulls, and Terns in California A Catalogue, Digital Atlas, and Conservation Tool W. DAVI D SHUFOR D Wildlife Branch Nongame Wildlife Program Report 2010-01 California Department of Fish and Game, Sacramento Author contact information: W. David Shuford PRBO Conservation Science 3820 Cypress Drive #11 Petaluma, CA 94954 [email protected] www.prbo.org Typography and design: Timothy W. Brittain Cover photo: Forster’s Tern (Sterna forsteri) at its nest on an algae mat by tule (Scirpus acutus) clumps at Tule Lake National Wildlife Refuge Sump 1-A, Siskiyou County, California, 20 June 1997. This and all other photos by the author. Recommended Citations: Shuford, W. D. 2010. Inland-breeding pelicans, cormorants, gulls, and terns in California: A catalogue, digital atlas, and conservation tool. Wildlife Branch, Nongame Wildlife Program Report 2010-01. California Department of Fish and Game, Sacramento. Available at www.dfg.ca.gov/wildlife/nongame/waterbirdcatalogue/. When referencing colony locations and maps, please cite the digital atlas CD-ROM of the catalogue as: Shuford, W. D., C. Rintoul, D. Stralberg, and V. Toniolo. 2010. Digital atlas of colonies of seven species of inland-breeding waterbirds in California, CD-ROM (Chapter 3) in Inland-breeding pelicans, cormorants, gulls, and terns in California: A catalogue, digital atlas, and conservation tool (W. D. Shuford, author/editor). Wildlife Branch, Nongame Wildlife Program Report 2010-01. California Department of Fish and Game, Sacramento. Available at www.dfg.ca.gov/wildlife/nongame/waterbirdcatalogue/. ii CONTENT S Frequently Used Acronyms .....................................................................iv Management and Research Recommendations .............................. 51 Acknowledgments ...................................................................................v Monitoring Needs ......................................................................... 51 Literature Cited ............................................................................ 52 Chapter 1. Abundance, Distribution, Habitat Use, Ring-billed Gull (Larus delawarensis) ................................................. 53 and Conservation Issues General Range and Abundance ..................................................... 53 Executive Summary ............................................................................. 3 Conservation Concern .................................................................. 55 Introduction ........................................................................................ 4 Seasonal Status in California.......................................................... 55 Study Area and Methods ..................................................................... 4 Breeding Range and Abundance in California ............................... 55 Background and Overall Approach .................................................. 4 Ecological Requirements ............................................................... 56 Northeastern California ................................................................... 5 Threats .......................................................................................... 57 American White Pelican and Double-crested Cormorant ............ 5 Management and Research Recommendations .............................. 58 Ring-billed Gull and California Gull ........................................... 6 Monitoring Needs ......................................................................... 59 Caspian Tern ............................................................................... 6 Literature Cited ............................................................................. 59 Black Tern and Forster’s Tern ....................................................... 7 California Gull (Larus californicus) .................................................... 59 Central Valley .................................................................................. 8 General Range and Abundance ..................................................... 59 Double-crested Cormorant .......................................................... 8 Conservation Concern .................................................................. 60 Caspian Tern ............................................................................... 9 Seasonal Status in California.......................................................... 60 Black Tern ................................................................................... 9 Breeding Range and Abundance in California ............................... 60 Forster’s Tern ............................................................................. 10 Ecological Requirements ............................................................... 61 Coast Ranges, Sierra Nevada Foothills, and Salton Sea .................. 10 Threats .......................................................................................... 63 Double-crested Cormorant ........................................................ 11 Management and Research Recommendations .............................. 63 Caspian Tern and Forster’s Tern ................................................. 12 Monitoring Needs ......................................................................... 64 Corrections and Additions to Published Accounts ......................... 12 Literature Cited ............................................................................. 64 Digital Atlas .................................................................................. 12 Caspian Tern (Hydroprogne caspia) ..................................................... 65 Mapping Approach ....................................................................... 12 General Range and Abundance ..................................................... 65 Digital Colony Maps ..................................................................... 13 Conservation Concern .................................................................. 65 Range Maps .................................................................................. 13 Seasonal Status in California.......................................................... 66 Results and Discussion ...................................................................... 13 Breeding Range and Abundance in California ............................... 66 Abundance .................................................................................... 14 Ecological Requirements ............................................................... 67 Distribution .................................................................................. 14 Threats .......................................................................................... 69 Nesting Habitat Use ...................................................................... 22 Management and Research Recommendations .............................. 69 Historic Trends .............................................................................. 22 Monitoring Needs ......................................................................... 69 Sites or Regions of Importance ...................................................... 23 Literature Cited ............................................................................. 69 Klamath Basin ........................................................................... 24 Black Tern (Chlidonias niger) ............................................................ 71 Modoc Plateau, Great Basin, and Sierra Nevada ........................ 24 General Range and Abundance ..................................................... 71 Central Valley ............................................................................ 25 Conservation Concern .................................................................. 71 Salton Sea .................................................................................. 26 Seasonal Status in California.......................................................... 71 Conservation Status ....................................................................... 26 Breeding Range and Abundance in California ............................... 71 North American Waterbird Conservation Plan .......................... 26 Northeastern California ............................................................. 74 Birds of Conservation Concern 2002 ........................................ 26 Central Valley ............................................................................ 74 California Bird Species of Special Concern ................................ 26 Migratory Stopovers .................................................................. 76 Conservation and Management Issues ........................................... 26 Ecological Requirements ............................................................... 76 Secure Nesting Sites .................................................................. 26 Threats .......................................................................................... 77 High Quality Water................................................................... 27 Management and Research Recommendations .............................. 77 Regional Concerns .................................................................... 27 Monitoring Needs ......................................................................... 77 Research Needs ............................................................................