Western Riverside County Multiple Species Habitat Conservation Plan Biological Monitoring Program

2017 White-tailed Kite (Elanus leucurus) Survey Report

Location of the 2017 White-tailed Kite nest in San Timoteo Canyon. The nest tree is in the center of the photo, to the left of the transmission tower. The nest was constructed in one of the clumps of bigleaf mistletoe (Phoradendron leucarpum ssp. macrophyllum).

4 April 2018 2017 White-tailed Kite Survey Report

TABLE OF CONTENTS INTRODUCTION ...... 1

GOALS AND OBJECTIVES ...... 3

METHODS ...... 5

SURVEY DESIGN ...... 5

FIELD METHODS ...... 5

DATA ANALYSIS ...... 6

RESULTS ...... 6

DETECTIONS OF WHITE-TAILED KITES ...... 6

WHITE-TAILED KITE NESTING ...... 7

DISCUSSION ...... 8

DETECTIONS OF WHITE-TAILED KITES ...... 8

WHITE-TAILED KITE NESTING ...... 9

RECOMMENDATIONS ...... 9

ACKNOWLEDGEMENTS ...... 10

LIST OF TABLES Table 1. The most recent detections of White-tailed Kites within each of the MSHCP- designated Core Areas, and the total number of detections within each Core Area, 2005– 2017...... 7

LIST OF FIGURES Figure 1. White-tailed Kite Core Areas with detections and nests prior to the current reporting period...... 2 Figure 2. White-tailed Kite Core Areas with detections and nests within the current reporting period, and 2017 survey stations...... 4

LIST OF APPENDICES Appendix A. Avian species detected during 2017 White-tailed Kite surveys. Species in bold are covered by the MSHCP...... 13

Western Riverside County MSHCP ii Biological Monitoring Program 2017 White-tailed Kite Survey 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 2017 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 2017 Avian Program Lead, Nicholas Peterson. This report should be cited as: Biological Monitoring Program. 2018. Western Riverside County MSHCP Biological Monitoring Program 2017 White-tailed Kite (Elanus leucurus) Survey Report. Prepared for the Western Riverside County Multiple Species Habitat Conservation Plan. Riverside, CA. Available from: http://wrc-rca.org/about-rca/monitoring/monitoring-surveys/. While we have made every effort to accurately represent our data and results, it should be recognized that data management and analysis are ongoing activities. Any reader 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 4500 Glenwood Drive, Bldg. C 3403 10th Street, Suite 320 Riverside, CA 92501 Riverside, CA 92501 Ph: (951) 248-2552 Ph: (951) 955-9700

Western Riverside County MSHCP iii Biological Monitoring Program 2017 White-tailed Kite Survey Report

INTRODUCTION The White-tailed Kite (Elanus leucurus) is one of 45 bird species covered by the Western Riverside County MSHCP (Dudek & Associates 2003) and is a California Fully Protected Species (FGC § 3511). Five species objectives are identified for this species. Objective 1 requires the conservation of at least 19,880 ac (8045 ha) of suitable breeding habitat, including riparian scrub, woodland, and forest; peninsular juniper woodland and scrub; and oak woodland and forests within the Riverside Lowlands, Santa Ana Mountains, and San Jacinto Foothills Bioregions. Objective 2 requires inclusion in the MSHCP Conservation Area of at least 10 Core Areas, including Lake Mathews-Estelle Mountain, Lake Perris/Mystic Lake, Lake Skinner including the Diamond Valley Lake area, Murrieta Creek, Prado Basin/Santa Ana River, Temecula Creek, Temescal Wash, Vail Lake, Wasson Canyon, and Wilson Valley (Fig. 1). Objective 3 requires the conservation of at least 281,890 ac (114,077 ha) of suitable foraging habitat, including agriculture, grasslands, cismontane alkali marsh, playas and vernal pools, freshwater marsh, Riversidean alluvial fan sage scrub, and chaparral within the Riverside Lowlands, Santa Ana Mountains, and San Jacinto Foothills Bioregions. Objective 4 requires the inclusion of the known winter roost area along San Timoteo Creek and any additional winter roost locations identified in the future. Such roost sites will be protected by a 250- m buffer of conserved, undeveloped habitat. Finally, Objective 5 requires maintaining the continued use of, and successful reproduction in, at least 75 percent of the Core Areas every three years (Dudek & Associates 2003). In addition to the habitats identified in the MSHCP, kites inhabit wetlands and savannahs adjacent to open areas (Dunk 1995). White-tailed Kites also require habitat that supports populations of diurnal small mammal prey such as California voles (Microtus californicus), harvest mice (Reithrodontomys megalotis), and house mice (Mus musculus) (Pickwell 1930; Hawbecker 1940; Moore and Barr 1941; Bond 1942; Dixon et al. 1957; Waian and Stendall 1970; Stendell and Myers 1973; Warner and Rudd 1975; Scheibler 2004, 2007). Finally, Kites require trees or shrubs for their nests, and these substrates can range in size from <3 m tall to >50 m tall (Stendell 1972; Dunk 1995). White-tailed Kites may remain paired throughout the year and courtship can occur from December through September. Nest construction occurs from January through August and nest substrates can be isolated or within contiguous stands of forest. Most nest sites are on habitat edges and >100 m from roadways and nests are generally located in the upper third of the substrate (Dunk 1995). Egg-laying in southern California can begin in early February (Dixon et al. 1957). Clutches typically contain 3–5 eggs (Barlow 1897; Pickwell 1930; Hawbecker 1942; Dixon et al. 1957) and the female is the sole incubator (Watson 1940; Hawbecker 1942; Dixon et al. 1957). The eggs hatch after an incubation period of 30–32 days (Hawbecker 1942) and young fledge 4 to 5 weeks later (Waian 1973). Young kites remain dependent on their parents for 2 to 3 months after fledging (Dixon et al. 1957). Finally, adult kites may attempt a second brood, sometimes before young from the first are independent (Hawbecker 1942; Stendell 1972; Wright 1978).

Western Riverside County MSHCP 1 Biological Monitoring Program Ä60 Legend

CALIMESA White-tailed Kite nest #* #*#* #* #* ¦¨§15 #*#* 215 #*#*#*#* !( #*#*#*#*#* #* ¦¨§ #*#* Prior to current reporting period (2011) EASTVALE #* San Timoteo #*#* 10 #*#* ¦¨§ Prado Basin/ Canyon #*#* White-tailed Kite detection RIVERSIDE Ä60 #* BEAUMONT Santa Ana River BANNING #* #* MORENO VALLEY Prior to current reporting period (2005-2014) #*#*#*#* NORCO #* Ä91 #*#* Highways #*#*#*#*#*#*#* #*#* Ä79 Lake Mathews/ #*#*#*#* #*#*#*#*#*#* #* #* #*#*#* #*#*#* #* #* Water Bodies Estelle Mountain #* #*#*#*#*#*#*#*#* #* #*#*#*#* #*#*#*#*#*#*#*#*#* #* Ä243 #* #*#* #*#* #*#*#*#* #* #*#*#*#*#*#*#* Existing Conservation Land CORONA #* #* #* #* #*#*#*#*#*#* #*#*#*#*#* #* #* #* #*#*#*#* #* #*#*#*#* #* #* Cities §15 #* Lake Perris/Mystic Lake ¦¨ #* #* #* 215 #* #*#*#*#*#*#*#* #*¦¨§ #* #*#* #* SAN JACINTO PERRIS #*#*#* Temescal Wash #* #* #* San Jacinto River #* #* #* #*#*#* #* #* #* #* #* Ä74 #* #* #* HEMET #*#*#* #* #* Ä74 #*#* Ä74 #* #*#* #*#* #* #* #* MENIFEE LAKE ELSINORE #*#*#* Wasson Canyon Lake Skinner/Diamond Valley Lake #*#* #* 215 #* #* #* #* ¦¨§ #*#*#*#* #* #* White-tailed Kite Core Areas #* #* WILDOMAR #* #* #*#*#*#*#* Ä79 #*#*#*#*#*#*#*#* #* #* #*#*#*#*#* Lake Mathews/Estelle Mountain §15 #*#*#* #*#*!(#*#*#* ¦¨ #*#*#* #*#*#*#*#*#*#*#* #* #* #*#*#* Lake Perris/Mystic Lake #* #*#*#*#*#*#* #*#* MURRIETA #*#*#*#*#*#* #* #* #*#*#*#*#* Wilson Valley Lake Skinner/Diamond Valley Lake #* #*#* Ä3#*71 #*#*#*#*#*#*#*#*#*#*#* Ä #*#*#*#* #*#*#* #* Murrieta Creek #*#*#* Murrieta Creek #* #* #* #* #* #* #* #* #* Prado Basin/Santa Ana River #* TEMECULA Vail Lake #* #* #* #* Ä79 Temecula Creek #* #* #* #* Temescal Wash ¦¨§15 Temecula Creek Vail Lake Date: 09 February 2018 Wasson Canyon UTM Nad 83 Zone 11 Wilson Valley km Contact: Nicholas Peterson I 0 2.5 5 10 15 20 MSHCP Biological Monitoring Program

Figure 1. White-tailed Kite Core Areas with detections and nests prior to the current reporting period.

2017 White-tailed Kite Survey Report

White-tailed Kites are permanent residents in much of California, including coastal areas, west of the Sierra Nevada foothills, the Central Valley, and arid regions of southern California (Small 1994). Kites also breed occasionally in western Oregon (Gilligan et al. 1994) and southwestern Washington (Palmer 1988). Kites commonly breed in southern Texas and periodically in extreme southern Florida (Robertson and Woolfenden 1992). Prior to the 2017 survey effort, our biologists detected White-tailed Kites 664 times within western Riverside County since 2005. More than 60% of these detections were within the Lake Mathews-Estelle Mountain (n = 44 detections), Lake Perris/Mystic Lake (n = 155), or Lake Skinner/Diamond Valley Lake (n = 202) Core Areas. Additionally, we had 43 kite observations in the Potrero Unit of the San Jacinto Wildlife Area (WA), 37 observations in or near the Santa Rosa Plateau Ecological Reserve, and 29 observations along San Timoteo Canyon, none of which are currently Core Areas for the species (Figs. 1 and 2). Also prior to the 2017 survey effort, our biologists have found four kite nests since 2008. The first, found in 2008, was in the Prado Basin/Santa Ana River and fledged young. The nest found in 2011 was within the Lake Skinner/Diamond Valley Lake Core Area and fledged at least three young. These two nests were more thoroughly described in the 2011 Riparian Bird Surveys and Nest Monitoring Report (Biological Monitoring Program 2012). The third, found in 2015 along San Timoteo Canyon, apparently failed during the incubation stage. The fourth nest, found in 2016 along the San Jacinto River north of Kabian Park, produced three fledglings (Figs. 1 and 2). The nests found in 2015 and 2016 will be fully described in the Results section of this report. Goals and Objectives 1. Document the distribution and density of White-tailed Kites in the MSHCP- identified Core Areas, and determine whether the species is successfully reproducing in at least 75% of the Core Areas. a. Conduct repeat-visit line transect surveys within accessible White-tailed Kite habitat in the Plan Area, recording all bird species observed. b. Collect data on kites seen perpendicular to our transects to determine their density within the survey areas. c. Search for and monitor any kite nests found on Conserved Land within the Plan Area. We will monitor nests until they fledge young or fail. 2. Determine the optimum number of survey stations and visits to each survey station, based upon detection data collected in 2017. This information, derived from detection probability and occupancy, represents the most efficient standard design possible (MacKenzie et al. 2006) a. Calculate the detection probability and occupancy of White-tailed Kites within the study area, then use these data to determine the optimum number of visits (Table 6.1, MacKenzie et al. 2006) and survey stations (Equation 6.3, MacKenzie et al. 2006) for future kite surveys.

Western Riverside County MSHCP 3 Biological Monitoring Program Ä60 Legend # CALIMESA White-tailed Kite nest 15 215 * ¦¨§ § !( !( !(!( !(!( ¦¨ San Timoteo *#!( Current reporting period (2015-2017) EASTVALE *# 10 Canyon ¦¨§ Prado Basin/ White-tailed Kite detection RIVERSIDE Ä60 BEAUMONT Santa Ana River BANNING *# !(*#!(!( !( MORENO VALLEY Current reporting period (2015-2017) *# NORCO Ä91 #!( Ä !( Survey stations * *#!(*# *# Ä79 Lake Mathews/ !( *#!(!( !( !( !( !(!( *# 2017 White-tailed Kite survey station Estelle Mountain *# *# !(!(*# !( *# !( Ä243 !( !( !( !( *# Highways CORONA *# *# !(!(!(!( !( !( !( !( Water Bodies 15 Lake Perris/Mystic Lake ¦¨§ !( !( 215 !( ¦¨§ Existing Conservation Land !( !(!(!( !( SAN JACINTO Cities PERRIS *#*# Temescal Wash *# San Jacinto *# River #*!( *# * Ä74 Ä HEMET Ä74 Ä74 Wasson Canyon !(!( *# MENIFEE LAKE ELSINORE 215 !( ¦¨§ !(!(!( *# *# Lake Skinner/Diamond Valley Lake White-tailed Kite Core Areas WILDOMAR *# Ä79 *# Lake Mathews/Estelle Mountain ¦¨§15 *# !( !(!(!( !(!( !( !( Lake Perris/Mystic Lake MURRIETA !(!(!(!(!( !( !( Wilson Valley Lake Skinner/Diamond Valley Lake Ä3*#71 !(!( !( Murrieta Creek Murrieta Creek !( !( *# !( !( Prado Basin/Santa Ana River Vail Lake Temecula Creek TEMECULA Ä79 Temecula Creek !( Temescal Wash 15 ¦¨§ *# Vail Lake Date: 09 February 2018 Wasson Canyon UTM Nad 83 Zone 11 Wilson Valley km Contact: Nicholas Peterson I 0 2.5 5 10 15 20 MSHCP Biological Monitoring Program

Figure 2. White-tailed Kite Core Areas with detections and nests within the current reporting period, and 2017 survey stations.

2017 White-tailed Kite Survey Report

METHODS Survey Design We conducted surveys for White-tailed Kites by making repeat visits (n = 2 or 3 visits) to line transects (n = 71 transects) within the MSHCP-identified Core Areas (Fig. 2). I began study site selection by identifying apparently suitable White-tailed Kite habitat on Conserved Lands within the MSHCP-identified Core Areas. These habitats were selected from our ArcGIS (ESRI 2006) vegetation layer (CDFG et al. 2005) and were based upon the habitat types in which our biologists have most often detected kites from 2005–2016, namely annual grassland; coastal oak woodland; coastal scrub; cropland, orchard, and vineyard; fresh emergent wetland; lacustrine; valley foothill riparian; and wet meadow. Finally, I generated 71 transects that were 150–500 m long and separated by at least 300 m, within the patches of apparently suitable kite habitat. Transects were oriented in a north-south direction (Buckland et al. 2015), except where this was not feasible due to the configuration of small parcels of Conserved Land. Field Methods Surveys began on 10 January 2017 and we conducted our final surveys on 21 April. Surveys occurred during the four hours following sunrise or the four hours preceding sunset, both of which generally represent periods of daily peak activity for White-tailed Kites (Warner and Rudd 1975; Jaksić et al. 1987). We terminated surveys during any periods of rain (Warner and Rudd 1975) or dense fog or if the ambient temperature exceeded 35 °C. White-tailed Kites will occasionally hunt in high or gusty winds (Warner and Rudd 1975), so we did not terminate surveys due to wind speed unless there were safety concerns for our biologists. At the beginning of the survey (i.e., at one of the transect termini), observers recorded on their datasheet the transect start time, ambient temperature (°C), and sky conditions. Observers then surveyed transects beginning at one of the transect termini and navigating to the central point, and then to the opposite terminus of the transect, ensuring that they remained along a straight path during the survey. Observers attempted to walk at a constant speed while surveying for kites, spending a minimum of 15 min walking the length of the transect. For each perched kite encountered perpendicular to the transect, observers recorded its distance (m), determined using a laser rangefinder, and the sighting angle (°) to the bird relative to the transect. If a kite was detected and it was not perpendicular to the transect, the observer still recorded on the datasheet the presence of the bird, but the distance and sighting angle were not recorded. Observers did not record the sighting angle or distance to kites that were flying because accurately measuring such distances with a rangefinder would be difficult or impossible. Instead, the observer recorded the sighting angle and distance if the kite eventually perched perpendicular to the transect. If the kite never perched perpendicular to the transect, then the observer still recorded the kite detection on their datasheet, leaving blank the sighting angle and distance categories. If we detected a kite during a survey, observers spent as much time as necessary to determine whether the kite had an active nest nearby. This could be done while either standing on the transect and observing the kite, or following completion of the transect

Western Riverside County MSHCP 5 Biological Monitoring Program 2017 White-tailed Kite Survey Report

survey. On a weekly basis, we visited all active kite nests found in 2017. Such follow-up visits occurred at a distance from which the observer could determine nest status based upon kite behavior, but not so close that the kites were disturbed. We continued monitoring active nests until fledging or failure occurred. The survey methods are more completely described in the Western Riverside County MSHCP Biological Monitoring Program 2017 White-tailed Kite Survey Protocol. Data Analysis I developed distance sampling survey methods using techniques described in Buckland et al. (2001) and Rosenstock et al. (2002). The design I used allows for the calculation of kite density, transect-level detection probability (p), and can be used to evaluate correlations between covariates (MacKenzie et al. 2006). I intended to use Program DISTANCE to conduct distance sampling analysis, provided we had distance data for a minimum of 60–80 kite detections perpendicular to our transects (Buckland et al. 2001). Distance sampling allows for density estimation with incomplete detection of animals (i.e., not all animals present need to be observed to estimate density). The method relies on fitting data to several pre-defined detection functions based upon the assumption that animals are less detectable with increasing distance from the observer (Buckland et al. 2001). Distance sampling also requires that the following four assumptions be met: 1) animals are distributed independently of the survey stations, 2) animals on the transect line are detected with certainty, 3) distance measurements are exact, and 4) animals are detected at their initial location (Buckland et al. 2015).

RESULTS Detections of White-tailed Kites We detected 120 avian species during our 2017 White-tailed Kite surveys, including 30 covered by the MSHCP (Appendix A). We detected kites along four transects in 2017, all of which occurred during our first round of surveys. We also had 20 kite detections in 2017 that did not occur during our survey effort (Fig. 2). From 2005– 2017 our Program biologists have detected kites 688 times in the Plan Area, with a maximum count in 2006 (n = 224 detections) and a minimum count in 2013 (n = 4). We detect an average (± SE) of 52.9 ± 18.1 kites per year and we have not met or exceeded that average since 2012, when we detected kites 82 times in the Plan Area. The two years during which we most frequently detected kites were 2006 and 2011 (224 and 154 detections, respectively), which followed the two wettest years in western Riverside County from 2005–2017 (NOAA 2017). We have detected kites in four (40%) of their Core Areas within the current three- year reporting period (2015–2017), which falls below the 75% threshold identified in the Species Objective. The four Core Areas in which we have detected kites during the current reporting period include Lake Perris/Mystic Lake, Lake Skinner/Diamond Valley Lake, Prado Basin/Santa Ana River, and Wasson Canyon. We have detected kites at five additional Core Areas prior to the current reporting period (Table 1). The last three- consecutive-year period during which we detected kites in ≥75% of their Core Areas was 2011–2013.

Western Riverside County MSHCP 6 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Table 1. The most recent detections of White-tailed Kites within each of the MSHCP-designated Core Areas, and the total number of detections within each Core Area, 2005–2017. Parenthetical years precede the current reporting period (2015–2017).

Core Area Most Recent Detection n detections (2005–2017) Lake Mathews/Estelle Mountain (2014) 46 Lake Perris/Mystic Lake 2017 187 Lake Skinner/Diamond Valley Lake 2016 204 Murrieta Creek (2012) 10 Prado Basin/Santa Ana River 2017 26 Temecula Creek (2011) 2 Temescal Wash Never 0 Vail Lake (2007) 5 Wasson Canyon 2015 12 Wilson Valley (2012) 4

We had distance data for just four kites in 2017, which falls far below the minimum recommendation of 60–80 detections required for distance sampling analysis (Buckland et al. 2001). I was also unable to calculate the optimum number of visits and survey stations for future surveys (MacKenzie et al. 2006) due to our small number of transect-level kite detections in 2017. White-tailed Kite Nesting We have not documented successful nesting by White-tailed Kites within at least 75% of their Core Areas during any three-year reporting period. Further, we have never found more than one nest during any given year. Descriptions of nest sites within the current reporting period are provided below. The nest we found in 2015 was within the San Timoteo Canyon area, approximately 4.3 km south of Calimesa (Fig. 2). The nest was approximately 15 m above ground and was constructed in a California live oak (Quercus agrifolia) that was approximately 17 m tall. We detected this pair on 10 July 2015. The pair copulated and the female then flew to the nest. The female was on the nest on 16 and 24 July but left briefly on 24 July, during which time two Common Ravens (Corvus corax) flew to the vicinity of the nest site. The female was again on the nest, likely incubating, on 30 July. On 6 August we did not see any kites in the area and the nest appeared to be abandoned. Three Common Ravens, one adult and two juveniles, flew directly to the kite nest on this date and we subsequently concluded that the nest had failed. The nest we found in 2016 was along the San Jacinto River, approximately 4 km south of Perris (Fig. 2). The nest was approximately 11 m above ground and was constructed in a willow (Salix spp.) that was approximately 20 m tall. We detected this pair on 22 January 2016, at which time both adults were contributing to the construction of the nest. We saw one of the adults continuing to construct the nest on 3 February. We observed the female on the nest from 9 February to 15 March, which likely covered the entire incubation period as well as the early nestling stage. We observed food deliveries

Western Riverside County MSHCP 7 Biological Monitoring Program 2017 White-tailed Kite Survey Report

to the nestlings on 18 March and 14 April. On 26 April we observed three fledglings within 200 m of the nest, with one of the adults. The nest we found in 2017 was within 600 m of the kite nest we monitored in 2015 (Fig. 2). The nest was 17.3 m above ground and located in a clump of bigleaf mistletoe (Phoradendron leucarpum ssp. macrophyllum) growing on a Goodding’s black willow (Salix gooddingii) that was 20.6 m tall. We detected the kite pair at this site on 25 January 2017. The pair interacted and copulated on this date and the male performed a flutter flight in the immediate vicinity of the eventual nest site. We observed copulation again on 2 and 24 February, and on 3 and 20 March. We observed the male bringing nesting material to the nest site on 24 February, and the female contributed nesting material on 3 March. The female was on the nest during most or all of our observation periods on 13, 20, and 27 March, and 3 and 7 April, during which time we assumed she was incubating. On 18 and 27 April we observed both adults about 100 m from the nest site and we never saw any food deliveries to the nest nor did we detect any sign of nestlings. By 5 May we were no longer detecting the pair at the site and we assumed the nest had failed.

DISCUSSION Detections of White-tailed Kites Investigators have known since the late 19th century that White-tailed Kite numbers in California have the potential to fluctuate dramatically (Barlow 1897). Causes for decline were blamed on increased human settlement and decreased prey abundance (Barlow 1897; Dixon et al. 1957). Statewide, kites were considered rare in the late 1930s and early 1940s (Fry 1966) but increased in abundance through the 1960s, likely due to increased agricultural activity (Warner and Rudd 1975) and concomitant increases in California vole populations under such conditions (Krebbs 1966). Aside from one study in which kites in California predominantly preyed upon house mice (Bond 1942), California voles apparently constitute the majority of prey items taken by kites in the state (Hawbecker 1940; Dixon et al. 1957; Waian and Stendell 1970; Stendell and Myers 1973). California voles require freestanding water and may congregate in wetter agricultural fields during dry summer months (Church 1966), leading to localized increases in kite populations (Warner and Rudd 1975). Years with above-average rainfall can also lead to increased California vole populations, thereby resulting in increases in kite abundance (Hawbecker 1940). Either of these scenarios could explain patterns in our kite detections from 2005 through 2017. First, we tend to see kites most consistently across years at the Davis Unit of the San Jacinto WA, which is within the Lake Perris/Mystic Lake Core Area (Figs. 1 and 2). The WA is managed for waterfowl and there is freestanding water year-round on agricultural fields on the property. Additionally, there is private property to the south of the WA that includes sod farms with freestanding water and access to prey. These properties were the source of diurnal small mammal prey for Northern Harriers (Circus hudsonius) nesting at the WA in 2009 (L. Miller, Biological Monitoring Program, personal observation).

Western Riverside County MSHCP 8 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Second, we have observed relatively more kites in years immediately following above-average rainfall years, particularly in 2006 and 2011. Some of these increases could be due to us conducting riparian bird surveys in 2006 and 2011, and thus being more likely to encounter kites; however, we also conducted riparian bird surveys in 2014 and 2017 but did not see notable increases in kite detections. Neither 2014 nor 2017 were above-average rainfall years for the Plan Area. White-tailed Kite Nesting The three kite nests we have found and monitored since 2015 were constructed in oaks or willows, which are two of the most common genera of substrates used by kites throughout the state. Other commonly-used substrates in California include cottonwood (Populus spp.), sycamore (Platanus spp.), and toyon (Heteromeles arbutifolia) (Barlow 1897; Pickwell 1930; Hawbecker 1940; Dixon et al. 1957). The nests we found were 11–17.3 m above ground, which is within the range of 7–18 m reported by Pickwell (1930). Dixon et al. (1957) indicated that kites seem to prefer nesting in trees of “moderate” height, which could describe the height range of substrates in this study (17–20.6 m). Eggs in San Diego County are laid as soon as early February (Dixon et al. 1957), which matches what we saw at our 2016 kite nest, when we saw the female incubating beginning on 9 February. Incubation at our 2017 nest started about one month later, beginning on 13 March. Mid-March is generally considered the peak of egg-laying and incubation, with the end of the peak occurring in late May (Dunk 1995). The nest we monitored in 2015 was apparently in the incubation stage in July, which is after the peak period of egg-laying and incubation and nearly completely outside of the period during which eggs are known to occur in kite nests (Dunk 1995). A nest this late in the season, and without any dependent young from an earlier nest, likely represented a second attempt following the failure of a first nest (Hawbecker 1940). Recommendations Future Surveys Our data indicate that White-tailed Kite detections in the Plan Area fluctuate based upon precipitation, with peak detection years following winters with above-average rainfall. To maximize our chances of documenting that kites are using ≥75% of their Core Areas, we should survey for the species in years following wet winters. Because wet winters have been occurring infrequently in southern California, we may want to conduct these surveys in addition to the regularly scheduled triennial surveys for kites. We have found few kite nests since 2005 so our biologists should continue to report to the Avian Program Lead any suspected nest sites, regardless of whether we are surveying for kites that year. We should also monitor the historic nesting territories each year to determine whether the site is being used again for nesting. For example, kites occupied and nested in the San Timoteo Canyon territory in both 2015 and 2017.

Western Riverside County MSHCP 9 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Core Area Definitions and Species Objectives I recommend designating San Timoteo Canyon (Proposed Linkages 5, 12, and 22) as a Core Area for White-tailed Kites. We have detected kites here at least 30 times since 2005 and have found two nests here since 2015. Further, I recommend designating Potrero (Subunit 1 of The Pass Area Plan) and Santa Rosa Plateau (Existing Core F plus Proposed Linkages 9 and 10 and Proposed Constrained Linkages 9–12) as Core Areas because we have detected kites here at least 43 and 37 times since 2005, respectively. Finally, Temescal Wash should be considered for removal as a Core Area for kites because we have never detected the species there despite our biologists conducting surveys for a variety of species since 2005.

ACKNOWLEDGEMENTS We thank the land managers in the MSHCP Plan Area who, in the interest of conservation and stewardship, facilitate Monitoring Program activities on the lands for which they are responsible. Funding for the Biological Monitoring Program is provided by the Western Riverside Regional Conservation Authority and the California Department of Fish and Wildlife. Program staff who conducted surveys in 2017 or monitored nests in 2015 or 2016 were Jessica Burton, Karyn Drennen, Tara Graham, Cristina Juran, Lynn Miller, Robert Packard, Nicholas Peterson, Esperanza Sandoval, and Ana Sawyer. Elizabeth Dionne (Riverside County Parks) provided nest-monitoring data on the 2016 kite nest.

LITERATURE CITED Barlow C 1897. Some notes on the nesting habits of the White-tailed Kite. Auk 14:14– 21. Biological Monitoring Program. 2012. Western Riverside County MSHCP Biological Monitoring Program 2011 Riparian Bird Surveys and Nest Monitoring Report. Prepared for the Western Riverside County Multiple Species Habitat Conservation Plan. Riverside, CA. Available from http://wrc-rca.org/about- rca/monitoring/monitoring-surveys/. Bond RM. 1942. White-tailed Kites feeding on house mice. Condor 44:231–232. Buckland ST, Anderson DR, Burnham KP, Laake JL, Borchers DL, Thomas L. 2001. Introduction to distance sampling: Estimating abundance of biological populations. Oxford University Press, Oxford. Buckland S.T, Rexstad EA, Marques TA, Oedekoven CS. 2015. Distance sampling: Methods and applications. Springer, Cham, Switzerland. CDFG (California Department of Fish and Game), Aerial Information Systems, California Native Plant Society. 2005. Vegetation - Western Riverside Co. [ds170]. Publication Date: 2005-07-31. Available from http://bios.dfg.ca.gov/ (accessed May 2016). Church R.L. 1966. Water exchanges in California vole (Microtus californicus). Physiological Zoology 39:326–340.

Western Riverside County MSHCP 10 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Dixon JB, Dixon RE, Dixon JE. 1957. Natural history of the White-tailed Kite in San Diego, California. Condor 59:156–165. Dudek & Associates. 2003. Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP). Final MSHCP, Volumes I and II. Prepared for County of Riverside Transportation and Lands Management Agency, Prepared by Dudek & Associates, Inc. Approved June 17, 2003. Dunk JR. 1995. White-tailed Kite (Elanus leucurus). In Rodenwald PG, editor. The Birds of North America. Cornell Lab of Ornithology, Ithaca, NY. Available from https://birdsna.org/Species-Account/bna/species/whtkit (accessed October 2016). ESRI (Environmental Systems Research Institute) ArcGIS: Release 9.3 [software]. Redlands, California: Environmental Systems Research Institute, 1999–2008. Fry DH Jr. 1966. Recovery of the White-tailed Kite. Pacific Discovery 19:27–30. Gilligan J, Rogers D, Smith M, Contreras A. 1994. Birds of Oregon: Status and distribution. Cinclus, McMinnville, OR. Hawbecker AC. 1940. The nesting of the White-tailed Kite in southern Santa Cruz County, California. Condor 42:106–111. Hawbecker AC. 1942. A life history study of the White-tailed Kite. Condor 44:267–276. Jaksić FM, Rozzi R, Labra A, Jiménez JE. 1987. The hunting behavior of Black- shouldered Kites (Elanus caeruleus leucurus) in central Chile. Condor 89:907– 911. Krebbs CJ. 1966. Demographic changes in fluctuating populations of Microtus californicus. Ecological Monographs 36:239–273. MacKenzie DI, Nichols JD, Royle JA, Pollack KH, Bailey LL, Hines JE. 2006. Occupancy estimation and modeling: Inferring patterns and dynamics of species occurrence. Elsevier, London. Moore RT, Barr A. 1941. Habits of the White-tailed Kite. Auk 58:453–462. NOAA (National Oceanic and Atmospheric Administration). 2017. Advanced Hydrologic Prediction Service: Precipitation Analysis. Available from https://water.weather.gov/precip/index.php (accessed November 2017). Palmer RS. 1988. Diurnal raptors. Pages 324–380 in Handbook of North American birds. Yale University Press, New Haven, CT. Pickwell G. 1930. The White-tailed Kite. Condor 32:221–239. Robertson WB Jr., Woolfenden GE. 1992. Florida bird species: An annotated list. Florida Ornithological Society Special Publication no. 6. Rosenstock SS, Anderson DR, Giesen KM, Leukering T, Carter MF. 2002. Landbird counting techniques: Current practices and an alternative. Auk 119:46–53. Scheibler DR. 2004. Geographic variation in the size of mammalian prey taken by White- tailed Kites in the Americas. Journal of Field Ornithology 75:218–222.

Western Riverside County MSHCP 11 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Scheibler DR. 2007. Food partitioning between White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in southern Brazil. Brazilian Journal of Biology 67:65–71. Small A. 1994. California birds: Their status and distribution. Ibis, Vista, CA. Stendell RC. 1972. The occurrence, food habits, and nesting strategy of White-tailed Kites in relation to a fluctuating vole population [PhD Dissertation]. University of California, Berkeley, CA. Stendell RC, Myers P. 1973. White-tailed Kite predation on a fluctuating vole population. Condor 75:359–360. Waian LB. 1973. The behavioral ecology of the North American White-tailed Kite (Elanus leucurus majusculus) of the Santa Barbara coastal plain [PhD Dissertation]. University of California, Santa Barbara, CA. Waian LB, Stendall RC. 1970. The White-tailed Kite in California with observations of the Santa Barbara population. California Fish and Game 56:188–198. Warner JS, Rudd RL. 1975. Hunting by the White-tailed Kite (Elanus leucurus). Condor 77:226–230. Watson FG. 1940. A behavior study of the White-tailed Kite. Condor 42:295–304.

Western Riverside County MSHCP 12 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Appendix A. Avian species detected during 2017 White-tailed Kite surveys. Species in bold are covered by the MSHCP.

COMMON NAME SCIENTIFIC NAME American Avocet Recurvirostra americana American Coot Fulica americana American Crow Corvus brachyrhynchos American Goldfinch Spinus tristis American Kestrel Falco sparverius American Pipit Anthus rubescens American Robin Turdus migratorius American White Pelican Pelecanus erythrorhynchos American Wigeon Anas americana Anna's Hummingbird Calypte anna Ash-throated Flycatcher Myiarchus cinerascens Bald Eagle Haliaeetus leucocephalus Barn Swallow Hirundo rustica Bell's Sparrow Artemisiospiza belli Bewick's Wren Thryomanes bewickii Black Phoebe Sayornis nigricans Black-necked Stilt Himantopus mexicanus Blue Grosbeak Passerina caerulea Blue-gray Gnatcatcher Polioptila caerulea Bonaparte's Gull Chroicocephalus philadelphia Brewer's Blackbird Euphagus cyanocephalus Bufflehead Bucephala albeola Bullock's Oriole Icterus bullockii Burrowing Owl Athene cunicularia Bushtit Psaltriparus minimus Cactus Wren Campylorhynchus brunneicapillus California Horned Lark Eremophila alpestris actia California Quail Callipepla californica California Scrub-Jay Aphelocoma californica California Thrasher Toxostoma redivivum California Towhee Melozone crissalis Canada Goose Branta canadensis Canyon Wren Catherpes mexicanus Cassin's Kingbird Tyrannus vociferans Cedar Waxwing Bombycilla cedrorum Cinnamon Teal Anas cyanoptera Cliff Swallow Petrochelidon pyrrhonota Coastal California Gnatcatcher Polioptila californica californica

Western Riverside County MSHCP 13 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Appendix A. Continued. COMMON NAME SCIENTIFIC NAME Common Raven Corvus corax Common Yellowthroat Geothlypis trichas Cooper's Hawk Accipiter cooperii Costa's Hummingbird Calypte costae Double-crested Cormorant Phalacrocorax auritus Downy Woodpecker Picoides pubescens Eared Grebe Podiceps nigricollis European Starling Sturnus vulgaris Ferruginous Hawk Buteo regalis Golden Eagle Aquila chrysaetos Grasshopper Sparrow Ammodramus savannarum Great Blue Heron Ardea herodias Great Egret Ardea alba Greater Roadrunner Geococcyx californianus Greater Yellowlegs Tringa melanoleuca Green-winged Teal Anas crecca Hooded Oriole Icterus cucullatus Horned Lark Eremophila alpestris House Finch Haemorhous mexicanus House Wren Troglodytes aedon Hutton's Vireo Vireo huttoni Killdeer Charadrius vociferus Lark Sparrow Chondestes grammacus Least Bell's Vireo Vireo bellii pusillus Least Sandpiper Calidris minutilla Lesser Goldfinch Spinus psaltria Lesser Scaup Aythya affinis Lincoln's Sparrow Melospiza lincolnii Loggerhead Shrike Lanius ludovicianus Long-billed Curlew Numenius americanus Mallard Anas platyrhynchos Marsh Wren Cistothorus palustris Merlin Falco columbarius Mountain Bluebird Sialia currucoides Mourning Dove Zenaida macroura Northern Flicker Colaptes auratus Northern Harrier Circus hudsonius Northern Mockingbird Mimus polyglottos Northern Pintail Anas acuta

Western Riverside County MSHCP 14 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Appendix A. Continued. COMMON NAME SCIENTIFIC NAME Northern Rough-winged Swallow Stelgidopteryx serripennis Northern Shoveler Anas clypeata Nuttall's Woodpecker Picoides nuttallii Osprey Pandion haliaetus Peregrine Falcon Falco peregrinus Phainopepla Phainopepla nitens Pied-billed Grebe Podilymbus podiceps Prairie Falcon Falco mexicanus Red-shouldered Hawk Buteo lineatus Red-tailed Hawk Buteo jamaicensis Red-winged Blackbird Agelaius phoeniceus Ring-billed Gull Larus delawarensis Ring-necked Duck Aythya collaris Rock pigeon Columba livia Rock Wren Salpinctes obsoletus Ruddy Duck Oxyura jamaicensis Sage Thrasher Oreoscoptes montanus Savannah Sparrow Passerculus sandwichensis Say's Phoebe Sayornis saya Sharp-shinned Hawk Accipiter striatus Short-eared Owl Asio flammeus Snowy Egret Egretta thula Song Sparrow Melospiza melodia Sora Porzana carolina Southern California Rufous-crowned Aimophila ruficeps canescens Sparrow Spotted Towhee Pipilo maculatus Tree Swallow Tachycineta bicolor Tricolored Blackbird Agelaius tricolor Turkey Vulture Cathartes aura Unidentified dove Family Columbidae Unidentified falcon Falco spp. Unidentified gull Family Laridae Unidentified hummingbird Family Trochilidae Unidentified kingbird Tyrannus spp. Unidentified sparrow Family Emberizidae Unidentified swallow Family Hirundinidae Unidentified woodpecker Family Picidae Vesper Sparrow Pooecetes gramineus

Western Riverside County MSHCP 15 Biological Monitoring Program 2017 White-tailed Kite Survey Report

Appendix A. Continued. COMMON NAME SCIENTIFIC NAME Violet-green Swallow Tachycineta thalassina Western Bluebird Sialia mexicana Western Kingbird Tyrannus verticalis Western Meadowlark Sturnella neglecta Western Tanager Piranga ludoviciana White-crowned Sparrow Zonotrichia leucophrys White-faced Ibis Plegadis chihi White-tailed Kite Elanus leucurus Wilson's Snipe Gallinago delicata Wrentit Chamaea fasciata Yellow Warbler Setophaga petechia Yellow-breasted Chat Icteria virens Yellow-rumped Warbler Setophaga coronata

Western Riverside County MSHCP 16 Biological Monitoring Program