Bird Surveys - Riverside County - 2012 [ds782]

This dataset represents special status and nesting species data collected during the spring and fall 2012 bird surveys at the proposed Rio Mesa SolarThermal Energy site located within the Colorado Desert region of the Sonoran Desert on the Palo Verde Mesa in Riverside County, California. The total project site is roughly 4,000 acres in size and is located on the east side of the Mule Mountains approximately 13 miles southwest of Blythe and 2 miles west of Palo Verde. The majority of the project site is on private lands owned by the Metropolitan Water District (MWD). Portions of the gen-tie line, secondary access road, and 33kV construction/emergency backup power supply line are located on public lands administered by the BLM. The project site is currently undeveloped and surrounded by undeveloped land to the north, south, and west with agricultural lands located to the east. The site is comprised primarily of creosote desert scrub with areas of desert wash scrub within the onsite washes. Portions of the site are disturbed due to existing infrastructure (transmission lines, pipelines, past military training activities, etc.). Spring 2012 bird surveys consisted of fixed-point observation counts, transect point counts and additional focused surveys for Elf Owl, Gila Woodpecker and nesting birds. Fall 2012 bird surveys consisted of fixed-point observation counts and transect point counts. For more details about the survey methodologies used, see below. Fixed-point observations consisted of four stations focused on non-raptors and three focused on raptors. These stations were located in areas that allowed a wide expanse of observation area from a single point while also being in areas with high potential for bird activity (e.g., adjacent to microphyll woodlands and areas with higher vegetation density). Stations were operated eight hours a day during the spring and fall seasons. Each non-raptor point was surveyed 3 times a week and each raptor point was surveyed 4 times a week. Surveys were performed under weather conditions with good visibility for detecting birds. Surveys were canceled during periods of sustained precipitation or fog, winds above 20 mph, and when temperature exceeded 105 degrees Fahrenheit (F). Information collected during surveys included: species, observation method (audio/visual), estimated distance from point, number of individuals, flight direction, estimated flight height, and information on the behavior of the bird. At each point all species of birds observed were counted. Transect surveys consisted of 16 transects with eight observation points per transect. Specific transect locations were chosen based on habitat characteristics where the highest density of avian species was likely to occur (e.g., microphyll woodland washes and areas with higher concentrations of vegetation). Out of 128 total survey points, 58 (45 percent) were located within microphyll woodland, and an additional 36 (28 percent) were located within 100 m of microphyll woodland. Transect locations were surveyed for all bird species on a weekly basis during spring and fall. Surveys started at sunrise and ended no later than 12:00 PM or when temperature exceeded 90F at the start of a transect. At most, biologists were able to survey two transects per day. A transect was not started if it was not possible to complete all eight points in a single day. Biologists began the survey at one end of a transect on the first point and surveyed systematically through the eight points in a transect in numerical order (recording any incidental sightings observed during transit between survey points). At each point, ten minutes were spent passively surveying for birds. All birds seen or heard at unlimited distance from the point were recorded. Information collected included: species, observation method (audio/visual), estimated distance from point, number of individuals, flight direction, estimated flight height, and information on the behavior of the bird. Three full-coverage Elf Owl surveys were conducted in all microphyll woodland habitats within and around the project site during the spring season. Elf Owl surveys were done by using a modified version of the survey protocol for the Cactus Ferruginous Pygmy-Owl (Glaucidium brasilianum cactorum) developed by the Arizona Game and Fish Department and USFWS because a standard survey protocol for Elf Owl has not been adopted by state or federal wildlife agencies. The modifications adopted included: allowing for increased spacing between broadcast stations; decreased playback and listening duration at each station; and altered survey timing. The results of this survey include the detection of two Elf Owls. These Elf Owl detections were previously submitted to CNDDB in 2012 and therefore are not included in this dataset. During the spring breeding season, eight full coverage surveys of the microphyll woodland within and around the project area were conducted for Gila Woodpecker and nesting birds. The survey protocol consisted of biologists, working in teams of 1 to 3 persons depending on the size of the washes being surveyed, slowly walking meandering transects through microphyll woodland habitat and playing recorded Gila Woodpecker calls every 100 meters to elicit a response from any Gila Woodpeckers that might have been in the vicinity. During call broadcast periods, the biologist would stop walking for roughly one minute scanning the surrounding area for bird movement and listening for Gila Woodpeckers. In areas with dense vegetation or where Gila Woodpeckers were previously detected, taped calls were broadcasted every 50 meters. All trees and dead snags with potential to support a Gila Woodpecker nesting cavity were visually searched for signs of nesting. If a Gila Woodpecker was detected, the following data would be recorded on the data sheets: GPS ID, coordinates, grid number, detection method (audio/visual), nest found (yes/no), and number of individuals along with any additional information observed such as age class, flight direction and if the observation was near a previously known location. Nest searches for all other birds occurred concurrently with the eight rounds of Gila Woodpecker surveys. Nest searching techniques included following behavioral clues, systematic searches of shrubs and trees and investigation of locations where flushed birds were first seen. If a nest was found, a GPS waypoint was taken and the following information was recorded on the field data sheet: date found, species, nest stage, grid number, GPS coordinates, GPS identifier, and notes on the substrate supporting the nest. Limitations of the data include the following assumptions: - Individuals were only counted once per day - Detectability was equal between species - Observer's hearing/visual ID ability equal between surveyors - All species were accurately identified