Enhancement of Tricolored Blackbird Breeding Habitat at the San Jacinto Wildlife Area Final Report prepared for: California Department of Fish and Wildlife LAG# P1382102 March 29, 2016 Prepared for: Western Riverside County Regional Conservation Authority Western Riverside County Multiple Species Habitat Conservation Plan 3403 10th Street, Suite 320, Riverside, CA 92501 Prepared by: Rosamonde R. Cook, PhD Enhancement of Tricolored Blackbird Breeding Habitat at the San Jacinto Wildlife Area This report and the project it describes are the result of collaboration between the California Department of Fish and Wildlife (CDFW) and the Western Riverside Regional Conservation Authority (RCA). Principle investigators included, in alphabetical order, Rosamonde Cook1 (RCA), Laurie Correa2 (RCA), Eddy Konno3 (CDFW), Adam Malisch1 (RCA), Nicholas Peterson1 (CDFW), Scott Sewell4 (CDFW), and Tom Trakes4 (CDFW). 1 Biological Monitoring Program, Western Riverside County Multiple Species Habitat Conservation Plan, 4500 Glenwood Drive, Building C, Riverside, CA 92501. 2 Western Riverside County Regional Conservation Authority, 3403 10th Street, #320, Riverside, CA 92501. 3 California Department of Fish and Wildlife, 78-078 Country Club Drive, #109, Bermuda Dunes, CA 92203. 4 California Department of Fish and Wildlife, 17050 Davis Road, Lakeview, CA 92567. ii Enhancement of Tricolored Blackbird Breeding Habitat at the San Jacinto Wildlife Area TABLE OF CONTENTS TABLE OF CONTENTS....................................................................................................................... iii LIST OF FIGURES ............................................................................................................................... v LIST OF TABLES ................................................................................................................................ vi INTRODUCTION ............................................................................................................................... 1 Taxonomic Status ........................................................................................................................ 1 Habitat Characteristics ................................................................................................................ 1 Population Demographics ........................................................................................................... 2 Conservation Status .................................................................................................................... 4 Population Status in the MSHCP ................................................................................................. 4 Project Goals and Objectives ...................................................................................................... 5 METHODS ........................................................................................................................................ 5 Study Site .................................................................................................................................... 6 Project Site Development ........................................................................................................... 8 Year One .................................................................................................................................. 8 Year Two ............................................................................................................................... 11 Monitoring ................................................................................................................................ 15 Tricolored Blackbirds ............................................................................................................ 15 Land Cover and Vegetation ................................................................................................... 16 Invertebrate Communities .................................................................................................... 16 Burrowing Owls and other Sensitive Bird Species ................................................................ 17 RESULTS......................................................................................................................................... 17 Habitat Enhancement ............................................................................................................... 17 Year One ................................................................................................................................ 17 Year Two ............................................................................................................................... 18 Occupancy and Habitat Use by Tricolored Blackbirds .............................................................. 21 2014 Breeding Season........................................................................................................... 21 2015 Breeding Season........................................................................................................... 22 2016 Breeding Season........................................................................................................... 31 Land Cover and Vegetation ....................................................................................................... 31 Invertebrate Communities ........................................................................................................ 32 Burrowing Owls and Other Sensitive Bird Species ................................................................... 36 DISCUSSION ................................................................................................................................... 38 Nesting Substrate ...................................................................................................................... 39 Foraging Habitat ........................................................................................................................ 39 Timing of Reproduction ............................................................................................................ 41 Management ............................................................................................................................. 41 Future Work .............................................................................................................................. 43 iii Enhancement of Tricolored Blackbird Breeding Habitat at the San Jacinto Wildlife Area Schedule for monitoring ....................................................................................................... 44 Cost savings and self-sufficiency ........................................................................................... 44 ACKNOWLEDGEMENTS ................................................................................................................. 45 REFERENCES .................................................................................................................................. 46 iv Enhancement of Tricolored Blackbird Breeding Habitat at the San Jacinto Wildlife Area LIST OF FIGURES Figure 2. Project sites showing subdivisions and metered water valves at Site 1. ........................ 9 Figure 3. One of five concrete flashboard water control boxes installed at Site 1. ..................... 10 Figure 4. Planting California wild rose on March 16, 2015. .......................................................... 11 Figure 5. Alfalfa field being irrigated by sprinklers on March 23, 2016. ...................................... 12 Figure 6. Student volunteers from Moreno Valley College and their professor, Dr. Joanna Werner-Fraczek. ............................................................................................................................ 13 Figure 7. Student volunteers from San Jacinto Valley College and their professor, Elliot Handrus. ....................................................................................................................................................... 13 Figure 8. Pink pin flags mark the location of planted California wild rose. .................................. 14 Figure 9. Drilling holes with a gas-powered auger to plant willow baccharis on a levee at Site 1. ....................................................................................................................................................... 15 Figure 10. Triticale seedlings at Site 1 on February 20, 2016. ....................................................... 19 Figure 11. Eastern side of triticale field with tricolored blackbirds on April 20, 2016. ................ 19 Figure 12. Western side of triticale field overgrown with rocket mustard on March 20, 2016. 20 Figure 13. Close-up view of alfalfa and rocket mustard at Site 1 on March 23, 2016. ................ 20 Figure 14. Extended area view of alfalfa at Site 1 on March 23, 2016. ........................................ 21 Figure 15. Location of tricolored blackbird breeding colonies in 2014 (blue markers) and 2015 (red markers). ............................................................................................................................... 22 Figure 16. Bridge Street Pond tricolored blackbird colony site. ................................................... 23 Figure 17. Spring-Summer Wetlands tricolored blackbird colony site. ........................................ 24 Figure 18. Mystic Lake