Abstract

A raptor survey was performed to identify locations of raptors along a proposed trunk sewer project. Nest locations were delineated on a hard copy aerial photograph and marked with a Global Positioning System (GPS) receiver unit. The locations of active raptor nests and bonding activity were digitized, and a resource map was created. A 500-foot buffer was created around all active nests. The accuracy of delineating the locations on the hard copy aerials, and eventually onto the “psuedo rectified” image files, was relatively high when compared to the GPS locations. However, GPS points facilitated the process of creating polygons corresponding to observed raptor bonding and territorial behavior,and data attributed to the points were essential in decribing behavior characteristics and localizing survey efforts. Accuracy of the raptor locations is also attributed to a high resolution photo with a high frequency of landmarks which enabled the surveys to be conducted with constant realization of the relative location of attributes within the project site.

Introduction
 
 

On behalf of the City of Roseville, a survey for nesting raptor species (birds of prey) was conducted within a 500-foot buffer of a proposed sewer alignment. The project area was located within Pleasant Grove and Roseville, California U.S. Geological Survey (USGS) 7.5- minute topographic quadrangles. The trunk sewer project covers a broad area of northwest Roseville, and when all segments are totaled, the linear project is approximately 3.7 miles long and 120 feet wide (includes trench width and construction easement). A map was prepared of the survey results with raptor nesting and bonding locations delineated using Arc View GIS.
 
 
 
 

Background
 
 

The proposed alignments will be constructed along habitat areas characterized as oak woodland, riparian oak woodland, disturbed grassland (cattle pasture), perennial creek watershed, agricultural (pistachio orchards), and rural residential/farm. A majority of the alignment follows disturbed annual grassland south of Pleasant Grove Creek. Pleasant Grove Creek is characterized by oak woodland and riparian oak woodland communities, consisting primarily of blue oak (Quercus douglasii), valley oak (Quercus lobata), and interior live oak (Quercus wislizenii); with some occurrences of black walnut (Juglans californica). Surrounding the alignment crossing of the south fork of Pleasant Grove Creek, riparian habitat exists dominated by interior live oak and blue oak, with a shrub layer of dense Himalayan blackberry (Rubus discolor) and poison oak (Toxidendron diversilobum). The oak woodland and riparian oak woodland habitat represents suitable nesting habitat for special status species including Swainson’s hawk (Buteo swainsoni), Cooper’s hawk (Accipiter cooperi), and white-tailed kite (Elanus leucurus). In addition, other raptor species not listed under special status, but fully protected from take by the California Fish and Game Code, section 3503.5, may also occupy the surrounding project habitat. Suitable nesting habitat within the 500-foot buffer of the project area was surveyed for nesting raptors.
 
 
 
 

Methods
 
 

Prior to conducting the field survey the following information sources were reviewed: § Project aerial photography § Pleasant Grove and Roseville, California USGS 7.5 minute topographic quadrangles. § The Roseville Regional Wastewater Service Area Master Plan: Draft Environmental Impact Report (Environmental Science Associates, 1996) § California Department of Fish and Game Natural Diversity Data Base report for the Pleasant Grove and Roseville, California U.S.G.S. 7.5-minute topographic quadrangles. § Field Guide to Birds of North America (National Geographic Society, 1992) § Birds of North America (Kaufman, 2000) Two field surveys were conducted by biologists Thomas Leeman and Jamie Galos on March 7, March 8, March 28, and March 29, 2001. Surveys were conducted by foot, and at all locations exhibiting potential nesting habitat. Each survey was conducted over two consecutive days. The locations of active raptor nests and observed bonding behavior were recorded with a Global Positioning System (GPS) Magellen Map 410 receiver. The locations were also delineated on aerial photographs provided by the City. The entities were then digitized onto the aerial photographs by utilizing Arc View GIS. The aerial photographs were “psuedo” rectified using various Arc View extensions and USGS quadrangles. The GPS unit provided a sort of ground truthing of the raptor locations with the understanding that accuracy of the GPS unit was approximately ± 10 feet. Recorded attributes for GPS points provided description of raptor behavior and location, and facilitated the creation of breeding and territorial boundary locations of raptor pairs.
 
 
 
 

Results
 
 

Two active raptor nests were observed during the survey within the 500-foot buffer. An active great horned owl (Bubo virginianus) nest was observed approximately 1750 feet west of the alignment crossing of Fiddyment Road along Pleasant Grove Creek. The nest was approximately 75 feet high in an interior live oak located on the north bank of Pleasant Grove Creek. The nest was constructed of sticks and is approximately 1.5 feet in diameter. During the March 28 field site visit, a pair of great horned owls was flushed from the nest area; one owl was seen leaving the nest. On the March 29 (last visit), a great horned owl was observed sitting on the nest. A pair of red-tailed hawks was observed on March 28 building a nest located near the western end of the Pleasant Grove alignment. The nest was located near the top of a large interior live oak on the north bank of Pleasant Grove Creek. One hawk was observed carrying nesting material, which it used for nest construction. On March 29, one red-tailed hawk was observed sitting on the nest, and did not flush from the location. Nest building activity was still being displayed. Many stick nests were observed within the alignment’s 500-foot buffer, although no other active nests were discovered. However, the project area was very active with pairs of raptors displaying bonding and breeding behaviors. The following behaviors were observed during the survey:

 A pair of American kestrels (Falco sparverius) was observed on March 28 and March 29 displaying bonding, breeding, and territorial behavior around the grass     land on the western end of the Pleasant Grove alignment. Most of the observed flight maneuvers and copulation took place on a dead oak tree filled with cavities.

 On all four site visits a pair of white-tailed kites was observed displaying bonding and breeding activity around the oak woodland riparian habitat approximately 200 to 700 feet east of Fiddyment Road, south of the north fork of Pleasant Grove Creek.

On March 28 and March 29, a pair of Swainson’s hawks was observed foraging and displaying bonding behavior in the open fields and oak woodland areas associated with the north fork of Pleasant Grove Creek. One hawk was observed over a stick nest within the area.

 On March 7 and March 8, a pair of white-tailed kites was observed displaying bonding and breeding activity around the oak woodland habitat near the eastern end of the Pleasant Grove allignment. On March 29, only a single white tailed-kite was observed in the same area displaying territorial behavior. Although an active nest was not found in the area, it is likely the other partner was siting on a nest.

 On March 29, a pair of red-shouldered hawks was observed displaying territorial and bonding behavior in the oak woodland area near the eastern end of the Pleasant Grove alignment.
 
 
 
 
 

Section of the proposed alignment with surveyed raptor locations.
 
 
 
 
 
 
 
 
 
 
 

Conclusion
 
 

Two active raptor nests were identified during the project site survey. The high volume of stick nests and raptor activity in the project area is indicative of further nesting activity. It is possible that additional nests within the 500-foot buffer from the alignment will become active before project activities are initiated. The locations of active raptor nests and bonding activity were digitized, and a corresponding 500-foot buffer was created around all active nests. The 500-foot buffer is commonly used by the California Department of Fish and Game when determing a no disturbance zone. The accuracy of delineating the locations on the hard copy aerials and eventually onto the “psuedo rectified” image files was relatively high when compared to the GPS locations. The accuracy can be attributed to a high resolution photo with a high frequency of landmarks which enabled the surveys to be conducted with constant realization of the relative location of attributes within the project site.
 
 
 
 

References
 
 

California Department of Fish and Game. January 2000. Natural Diversity Data Base Report for the Pleasant Grove and Roseville USGS 7.5-minute topographic quadrangles. Sacramento, CA.

 Cornell Laboratory of Ornithology. 1992. Western Song Birds. Houghton Miffin Company. New York, NY.

 Environmental Science Associates. May 1996. Roseville Wastewater Treatment Service Area Master Plan: Draft Environmental Impact Report. Prepared for the City of Roseville.

 Kaufman, K. 2000. Birds of North America. Houghton Miffin Company. New York, NY.

 National Geographic Society. 1992. Field Guide to the Birds of North America. Washington, D.C. , 1(1):5-23.