PETITION TO THE STATE OF CALIFORNIA FISH AND GAME COMMISSION SUPPORTING INFORMATION FOR The California Tiger Salamander (Ambystoma californiense) TABLE OF CONTENTS EXECUTIVE SUMMARY.................................................................................................................1 PROCEDURAL HISTORY ................................................................................................................2 THE CESA LISTING PROCESS AND THE STANDARD FOR ACCEPTANCE OF A PETITION ...5 DESCRIPTION, BIOLOGY, AND ECOLOGY OF THE CALIFORNIA TIGER SALAMANDER ....6 I. DESCRIPTION ...............................................................................................................................6 II. TAXONOMY .................................................................................................................................7 III. REPRODUCTION AND GROWTH .....................................................................................................7 IV. MOVEMENT.................................................................................................................................9 V. FEEDING ....................................................................................................................................10 VI. POPULATION GENETICS .............................................................................................................10 HABITAT REQUIREMENTS..........................................................................................................12 DISTRIBUTION ..............................................................................................................................13 I. HISTORICAL DISTRIBUTION ........................................................................................................13 II. CURRENT DISTRIBUTION ............................................................................................................14 A. Range-wide Distribution .......................................................................................................14 B. Sonoma County Distribution .................................................................................................17 C. Santa Barbara Distribution ...................................................................................................18 D. Central California Distribution .............................................................................................18 1. Bay Area Distribution........................................................................................................18 2. Central Valley Distribution................................................................................................19 3. Southern San Joaquin Distribution.....................................................................................19 4. Central Coast Range Distribution ......................................................................................19 ABUNDANCE AND POPULATION DECLINE..............................................................................20 NATURE AND DEGREE OF THREAT ...........................................................................................21 I. PRESENT OR THREATENED MODIFICATION OR DESTRUCTION OF HABITAT...................................22 A. Measures of Habitat Destruction Throughout the Range of the California Tiger Salamander23 1. Range-wide Decline ..........................................................................................................23 2. Continued Decline of Vernal Pools in California ...............................................................23 3. Other Studies of Habitat Conversion..................................................................................27 4. Destruction of Native Prairie Habitat.................................................................................28 5. Human Population Growth................................................................................................29 6. CNDDB and Environmental Review Documents...............................................................30 II. SPECIFIC THREATS BY POPULATION SEGMENT ............................................................................33 Page i A. Sonoma County .....................................................................................................................33 1. Status ................................................................................................................................33 2. Current Threats..................................................................................................................38 B. Santa Barbara.......................................................................................................................42 1. Specific Threats to the Santa Barbara County Population of the California Tiger Salamander as Presented by Sweet (1998)....................................................................................................46 C. Central California.................................................................................................................51 1. Current Threats..................................................................................................................51 a. Bay Area ..........................................................................................................................51 i. Alameda County........................................................................................................52 ii. Santa Clara County....................................................................................................54 iii. San Mateo County.....................................................................................................55 iv. San Benito County.....................................................................................................56 b. Central Valley ...............................................................................................................57 i. Contra Costa County..................................................................................................60 ii. Solano County...........................................................................................................63 iii. Sacramento County ...................................................................................................63 iv. Amador County.........................................................................................................63 v. San Joaquin County...................................................................................................64 vi. Stanislaus County......................................................................................................64 c. Southern San Joaquin Valley .........................................................................................64 d. Central Coast Range ......................................................................................................65 i. Monterey County.......................................................................................................65 ii. San Luis Obispo County............................................................................................66 III. REMAINING HABITAT ON EXISTING PROTECTED AND PUBLIC LAND IS INADEQUATE TO ENSURE THE LONG TERM SURVIVAL OF THE SPECIES.......................................................................................66 OVEREXPLOITATION...................................................................................................................72 PREDATION ...................................................................................................................................72 COMPETITION...............................................................................................................................73 DISEASE .........................................................................................................................................73 OTHER NATURAL EVENTS OR HUMAN-RELATED ACTIVITIES............................................74 I. HABITAT FRAGMENTATION ........................................................................................................74 II. HYBRIDIZATION WITH INTRODUCED TIGER SALAMANDERS ........................................................75 III. OTHER INTRODUCED SPECIES.....................................................................................................77 A. Mosquitofish..........................................................................................................................77 B. Other Introduced Fish Species...............................................................................................78 C. Bullfrogs ...............................................................................................................................78 C. Crayfish ................................................................................................................................78 D. Domestic Pets........................................................................................................................79 IV. CONTAMINANTS ........................................................................................................................79 A. Road Run-off.........................................................................................................................79 B. Agricultural Contaminants....................................................................................................80