Western Riverside County Multiple Species Habitat Conservation Plan Biological Monitoring Program 2019 Riparian Birds Survey and Nest Monitoring Report Yellow-breasted Chat nest in the Temescal Wash Core Area. Photo by Robert Packard. 15 April 2020 2019 Riparian Birds Survey and Nest Monitoring Report TABLE OF CONTENTS INTRODUCTION .................................................................................................................... 1 GOALS AND OBJECTIVES ................................................................................................................... 3 METHODS ............................................................................................................................ 3 SURVEY DESIGN ................................................................................................................................ 3 FIELD METHODS ................................................................................................................................ 4 RESULTS .............................................................................................................................. 4 DETECTIONS OF TARGET SPECIES ...................................................................................................... 4 NESTING OF TARGET SPECIES ............................................................................................................ 7 DISCUSSION ....................................................................................................................... 11 DETECTIONS OF TARGET SPECIES .................................................................................................... 11 NESTING OF TARGET SPECIES .......................................................................................................... 12 RECOMMENDATIONS ........................................................................................................................ 14 ACKNOWLEDGEMENTS ....................................................................................................... 14 LITERATURE CITED ............................................................................................................ 15 LIST OF TABLES Table 1. Most recent detections on currently conserved land of the two target species of our 2019 riparian bird surveys. ........................................................................................... 5 Table 2. Most recent evidence of successful reproduction on currently conserved land by the two target species of our 2019 riparian bird surveys. ................................................... 7 Table 3. Summary of 2019 Yellow Warbler nest counts, and the number of fledglings observed, by Core Area....................................................................................................... 7 LIST OF FIGURES Figure 1. Riparian bird Core Areas and stations surveyed in 2019 .................................... 2 Figure 2. Detection of Yellow Warblers within the Plan Area (2005-2019) ...................... 6 Figure 3. Detections of Yellow-breasted Chats within the Plan Area (2005-2019) ........... 8 Figure 4. Locations of Yellow Warbler nests and fledglings in 2019 ................................ 9 Figure 5. Locations of Yellow-breasted Chat nest and fledglings in 2019 ....................... 10 LIST OF APPENDICES Appendix A. Avian species detected during 2019 riparian bird surveys .......................... 18 Western Riverside County MSHCP ii Biological Monitoring Program 2019 Riparian Birds Survey and Nest Monitoring Report NOTE TO READER: This report is an account of survey activities conducted by the Biological Monitoring Program for the Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP). The MSHCP was permitted in June 2004. Reserve assembly is ongoing and is expected to take 20 or more years to complete. The Conservation Area includes lands acquired under the terms of the MSHCP and other lands that have conservation value in the Plan Area (called public or quasi-public lands in the MSHCP). In this report, the term “Conservation Area” refers to these lands as they were understood by the Monitoring Program at the time the surveys were conducted. The Monitoring Program monitors the status and distribution of the 146 species covered by the MSHCP within the Conservation Area to provide information to Permittees, land managers, the public, and the Wildlife Agencies [i.e., the California Department of Fish and Wildlife (CDFW, formerly California Department of Fish and Game) and the U.S. Fish and Wildlife Service]. Monitoring Program activities are guided by defined conservation objectives for each Covered Species, other information needs identified in MSHCP Section 5.3 or elsewhere in the document, and the information needs of the Permittees. A list of the lands where data collection activities were conducted in 2019 is included in Section 7.0 of the Western Riverside County Regional Conservation Authority (RCA) Annual Report to the Wildlife Agencies. The primary author of this report was the 2019 Avian Program Lead, Nicholas Peterson. This report should be cited as: Biological Monitoring Program. 2020. Western Riverside County MSHCP Biological Monitoring Program 2019 Riparian Birds Survey and Nest Monitoring Report. Prepared for the Western Riverside County Multiple Species Habitat Conservation Plan. Riverside, CA. Available online: http://wrc-rca.org/about-rca/monitoring/monitoring-surveys/. While we have made every effort to accurately represent our data and results, the reader should recognize that data management and analysis are ongoing activities. Anyone wishing to make further use of the information or data provided in this report should contact the Monitoring Program to ensure that they have access to the best available or most current data. Please contact the Monitoring Program Administrator with questions about the information provided in this report. Questions about the MSHCP should be directed to the Executive Director of the RCA. Further information on the MSHCP and the RCA can be found at www.wrc-rca.org. Contact Information: Executive Director Monitoring Program Administrator Western Riverside County Western Riverside County MSHCP Regional Conservation Authority Biological Monitoring Program Riverside Centre Building 1835 Chicago Ave., Suite C 3403 10th Street, Suite 320 Riverside, CA 92507 Riverside, CA 92501 Ph: (951) 320-2168 Ph: (951) 955-9700 Western Riverside County MSHCP iii Biological Monitoring Program 2019 Riparian Bird Survey and Nest Monitoring Report INTRODUCTION Thirteen bird species covered by the MSHCP inhabit riparian areas, including Cooper’s Hawk (Accipiter cooperii), Downy Woodpecker (Dryobates pubescens), Least Bell’s Vireo (Vireo bellii pusillus), MacGillivray’s Warbler (Geothlypis tolmiei), Nashville Warbler (Leiothlypis ruficapilla), Sharp-shinned Hawk (Accipiter striatus), Southwestern Willow Flycatcher (Empidonax traillii extimus), Tree Swallow (Tachycineta bicolor), Western Yellow-billed Cuckoo (Coccyzus americanus occidentalis), White-tailed Kite (Elanus leucurus), Wilson’s Warbler (Cardellina pusilla), Yellow-breasted Chat (Icteria virens), and Yellow Warbler (Setophaga petechia brewsteri). The Plan Area is part of the present or historical regular breeding range for the following nine of these Covered Species: Cooper’s Hawk, Downy Woodpecker, Least Bell’s Vireo, Southwestern Willow Flycatcher, Tree Swallow, White-tailed Kite, Yellow- billed Cuckoo, Yellow-breasted Chat, and Yellow Warbler. The remaining four species occur within the Plan Area only during migration, except for small, occasional breeding populations, particularly at higher elevations. The species objectives for Yellow Warbler and Yellow-breasted Chat require the demonstration of both use and successful reproduction within 75% of specified Core Areas (Fig. 1) every five years, and we last surveyed for them in 2014. Thus, these two species were the targets of our 2019 riparian bird surveys, but we also collected data on any other covered riparian bird species observed. The statewide population of Yellow Warblers is considered greatly reduced (>40– 80%) since population estimates reported by Grinnell and Miller (1944), with a current estimate of between 100,000 and 1,000,000 birds (Heath 2008). The range size of Yellow Warblers in California is moderately (>20–40%) reduced since the publication of Grinnell and Miller (1944). By 2028, habitat loss, habitat degradation, or other human- induced threats are projected to slightly reduce (>5–10%) the species’ population in California (Heath 2008). Breeding Yellow Warblers generally inhabit wet thickets of deciduous trees, especially those dominated by alders (Alnus spp.), cottonwoods (Populus spp.), or willows (Salix spp.) (Dunn and Garrett 1997; Garrett et al. 2012). Nesting occurs from May through August (Lowther et al. 1999), although the species arrives in western Riverside County in April, so earlier nesting dates are possible. Nests are usually constructed in trees, including willows, and are typically 1–2.5 m above ground, although nest heights up to 15 m have been documented (Trautman 1940; Graber et al. 1983; Peck and James 1987; Knopf and Sedgwick 1992; Briskie 1995; Lowther et al. 1999; Campbell et al. 2001). Clutches usually contain four or five eggs (Lowther et al. 1999) and the incubation period lasts for 11 or 12 days (Bigglestone 1913; Schrantz 1943; Briskie 1995; McMaster and Sealy 1998; Ortega 1998). Young typically