Avenal Energy AFC 

APPENDIX 6.6-4 

SWAINSON’S HAWK MONITORING REPORT 
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . Quality Biological Services Through Technical 

Proficiency and Experienced Management 

Bumgardner Biological Consulting 

September 20, 2007 

Joe Stenger 

TRC Solutions 

2666 Rodman Drive 

Los Osos, CA 93402 

Dear Mr. Stenger: 

This letter report provides the results of 2007 monitoring for Swainson’s hawk 

(Buteo swainsoni) between the site of the proposed Avenal Energy power project 

(Kings County) and California Department of Water Resources (DWR) Arroyo 

Pasajero Detention Basin (Fresno County) (Figure 1). The monitoring was 

conducted at the request of the California Department of Fish and Game (DFG) to 

determine if there is evidence of Swainson’s hawk foraging or other use within the 

electrical transmission line corridor between the proposed power plant site and 

Pacific Gas and Electric Company’s (PG&E) Gates Substation (i.e., route of the 6.4 

miles of new electrical transmission line proposed as part of the new power project). 

The lands between the site of the proposed Avenal Energy power plant (i.e., project 

site) and Arroyo Pasajero Detention Basin (i.e., detention basin) were selected for 

monitoring given that all local records of nesting Swainson’s hawk from DFG and 

DWR databases are from the detention basin (Figure 2). Therefore, it was assumed 

that daily movement of Swainson’s hawks in the area would originate from the 

vicinity of nest sites within the detention basin. Monitoring was conducted for a 

minimum of eight hours on each of six days over a three-week period of time 

between July 17 and August 1, 2007. Monitoring consisted of: (1) observing the 

electrical transmission line corridor from several fixed vantage points while 

watching for Swainson’s hawks and other raptors and (2) driving public roads and 

farm roads within the area while searching for roosting or soaring Swainson’s 

hawks. All raptors found within the area were observed and followed to the extent 

possible to maximize the amount of location and behavior data associated with the 

individual(s). The collected data associated with each observed raptor included the 

date, time, location, and behavior of the individual(s). 

Michael Bumgardner 

Bumgardner Biological Consulting 

11571 Prospect Hill Drive 

Gold River, CA 95670-8216 
September 20, 2007 

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The results of monitoring for Swainson’s hawk within the monitoring area are 

summarized in Table 1. The monitoring found no evidence of Swainson’s hawk 

foraging or other uses within the existing electrical transmission line corridor south 

of the Gates Substation. Furthermore, with one exception (an immature Swainson’s 

hawk observed sitting on a telephone pole on the south side of Jayne Avenue east of 

Lassen Avenue), no foraging or other uses by Swainson’s hawks were documented 

south of Jayne Avenue. These results are not unexpected given that most of the land 

south of Jayne Avenue is comprised of orchards (an unsuitable foraging habitat for 

Swainson’s hawk) while the lands north of Jayne Avenue, surrounding the City of 

Huron, and in the vicinity of the detention basin are comprised of field crops 

(typically tomatoes, cantaloupes, wheat, or onions) or non-native grassland. 

Consequently, Swainson’s hawks would not be expected to incur the bioenergetic 

costs of foraging further south over unsuitable foraging habitat when extensive 

acreage of suitable foraging habitat is located immediately adjacent to the known 

nest sites. 

Should you have any questions in regards to the surveys or information presented in 

this letter report please do not hesitate to contact me (916-638-7368). 

Michael Bumgardner 

Bumgardner Biological Consulting 
September 20, 2007 

Page 3 

Table 1 

2007 Swainson’s Hawk Monitoring Data 

for Lands near the Arroyo Pasajero Detention Basin (near the City of Huron)

Date/Time Location Notes 

07-17-07 

09:05 PST 

immediately northwest of Gale Avenue 

and San Luis Canal 

adult Swainson’s hawk soaring and calling; flew 

out of sight to northwest 

07-17-07 

09:22 PST 

0.3 miles north of the intersection of 

Gale Avenue and San Luis Canal 

immature Swainson’s hawk sitting and soaring 

over detention basin 

07-18-07 

07:40 PST 

0.3 miles north of the intersection of 

Gale Avenue and San Luis Canal 

immature Swainson’s hawk sitting and soaring 

over detention basin; mobbed by western kingbird 

07-18-07 

10:24 PST 

0.3 miles north of the intersection of 

Gale Avenue and San Luis Canal 

immature Swainson’s hawk sitting on canal 

embankment looking east (suggests that adults 

may be foraging over lands to east) 

07-23-07 

08:29 PST 

along Lassen Avenue 1.5 miles north 

of Huron 

adult Swainson’s hawk sitting on telephone pole 

east of Lassen Road; 2nd adult Swainson’s hawk 

sitting in low snag 100 yards east of Lassen Road; 

pair soared over dry grassland west of Lassen 

Avenue before flying out of sight to north 

07-23-07 

08:53 PST 

0.7 miles west of Gale Avenue and San 

Luis Canal (approximately 150 yards 

south of Gale Avenue) 

adult Swainson’s hawk sitting in disked onion 

field; moved 50 feet to avoid active plowing; 

eventually flew to harvested tomato field north of 

Gale Avenue and approximately 1 mile west of 

Gale Avenue and San Luis Canal; soared over 

field until flying out of sight to north with 2nd

individual 

07-23-07 

09:40 PST 

1.0 mile west of Gale Avenue and San 

Luis Canal (approximately 200 yards 

north of Gale Avenue) 

Swainson’s hawk (age unknown) joined soaring 

individual and soared over tomato field north of 

Gale Avenue until flying out of sight to north 

07-24-07 

07:10 PST 

0.3 miles north of the intersection of 

Gale Avenue and San Luis Canal 

immature Swainson’s hawk sitting in detention 

basin; flushed and flew to large cottonwood on 

west side of basin 

07-24-07 

07:54 PST 

along Lassen Avenue 1.5 miles north 

of Huron 

adult Swainson’s hawk sitting on low snag 50 

yards west of Lassen Avenue in dry grassland; 

flew out of sight to southeast 

07-24-07 

08:07 PST 

1.4 miles north of Huron and 0.9 miles 

east of Lassen Avenue 

adult Swainson’s hawk sitting on telephone pole 

along farm road adjacent to DWR lands (same 

individual from 07:54 PST?); soared over dry 

grassland to north until flying out of sight to north 

07-31-07 

19:57 PST 

along Lassen Avenue 1.4 miles north 

of Huron 

adult Swainson’s hawk sitting on telephone pole 

east of Lassen Road 
September 20, 2007 

Page 4 

08-01-07 

07:48 PST 

0.3 miles south of Jayne Avenue and 

0.4 miles west of Lassen Avenue 

adult red-tailed hawk sitting on telephone pole 

along farm road 

08-01-07 

08:01 PST 

immediately south of Jayne Avenue 

0.6 miles east of Lassen Avenue 

immature Swainson’s hawk sitting on telephone 

pole south of Jayne Avenue overlooking tomato 

field to north; disturbed by harvesting operations 

in adjacent pepper field; flew to grove of 

Eucalyptus sp. along road at 15721 Jayne Avenue 

08-01-07 

08:48 PST 

1.5 miles north of Huron and 0.9 miles 

east of Lassen Avenue 

adult red-tailed hawk sitting on ground along farm 

road 
September 20, 2007 

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Figure 1
September 20, 2007 

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Figure 2