Avenal Energy AFC 

APPENDIX 6.6-5 

AVIAN TRANSMISSION LINE MORTALITY REPORT 
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . Quality Biological Services Through Technical 

Proficiency and Experienced Management 

Bumgardner Biological Consulting 

February 1, 2007 

Joe Stenger 

TRC 

2666 Rodman Drive 

Los Osos, CA 93402 

Dear Mr. Stenger: 

As per a request from the California Department of Fish and Game (DFG), Bumgardner 

Biological Consulting (BBC) has conducted additional research into avian transmission 

line mortality in the vicinity of the five miles of additional electric transmission line that 

is associated with the proposed Avenal Energy Project (proposed project). The 

additional five miles of transmission line would be located adjacent to an existing 

Pacific Gas & Electric (PG&E) transmission line corridor located immediately south of 

the Gates Substation in Fresno and Kings counties. The existing transmission line 

corridor currently contains two parallel 500 kV lines and two 230 kV lines. 

BBC contacted Sheila Byrne (PG&E) on November 28, 2006 in regards to data that 

PG&E has collected on avian transmission line strikes along the subject PG&E 

transmission line corridor (pers. comm.). Ms. Byrnes is PG&E’s in-house technical 

expert on avian mortality associated with electric transmission lines and towers. Ms. 

Byrne was unaware of any avian mortality data collected by PG&E or other entities in 

the vicinity of the proposed project. Furthermore, she indicated that the existing 

transmission line corridor is not within an area that is known to be an avian migratory 

corridor or that attracts large numbers of birds. Therefore, the magnitude of avian line 

strikes in the area is likely negligible (if it occurs at all). Nonetheless, she suggested 

speaking with Mark Dedon (PG&E), Michael Best (PG&E), and John Bridges (Western 

Area Power Administration). 

Mr. Dedon is an in-house PG&E biologist who also has conducted substantial research 

on avian transmission line strikes. BBC contacted Mr. Dedon on December 6, 2006 

(pers. comm.). Mr. Dedon was not aware of any avian mortality associated with 

PG&E’s existing transmission line corridor south of the Gates Substation. Furthermore, 

Mr. Dedon indicated that he had conducted surveys within the transmission line corridor 

from the Gates Substation to the Midway Substation in 2002 and found no evidence of 

avian mortality that could be attributed to line strikes. Consequently, he concurred with 

Ms. Byrne’s assessment that the magnitude of avian line strikes in the project area is 

rare (if it occurs at all). 

Michael Bumgardner 

Bumgardner Biological Consulting 

11571 Prospect Hill Drive 

Gold River, CA 95670-8216 
February 1, 2007 

Page 2 

BBC also contacted John Bridges via e-mail on December 6, 2006. Mr. Bridges is an 

in-house expert on avian mortality associated with electric transmission lines and towers 

for the Western Area Power Administration (WAPA). Though most of his experience is 

from the Cosumnes River north, he responded via e-mail on December 7, 2006 that he is 

unaware of any avian mortality from line strikes in the vicinity of the proposed project. 

BBC also sent an e-mail to Michael Best on December 6, 2006 requesting information 

on power outages that could be attributed to avian transmission line strikes along the 

PG&E transmission line corridor south of the Gates substation. Mr. Best is PG&E’s 

Bird Protection Program Manager. He responded on December 14, 2006 that avian 

transmission line strikes rarely cause power outages and thus go undetected. However, 

he was not aware of any avian line strike issues in the vicinity of the proposed project. 

Most of the avian line strike incidents that he has dealt with have occurred further north 

in the San Joaquin and Sacramento valleys. 

Lastly, BBC conducted an internet search for information on known avian migration or 

movement corridors within the vicinity of the proposed project. This research resulted 

in no identification of known migration or movement corridors for avian species in the 

project vicinity. The nearest known migration corridor is the adjacent foothills of the 

Coast Ranges (where raptors routinely migrate along the ridgelines during fall 

migration). The absence of a known migration corridor in the project vicinity is not 

unexpected given the lack of local geographic characteristics that usually accompany 

such corridors (e.g., ridgelines, mountain gaps or passes, coast lines, substantial wetland 

resources, etc.). Furthermore, the area surrounding the existing transmission line 

corridor consists entirely of agricultural land uses. Therefore, the area does not provide 

the types of natural resources that attract large numbers of avian species (e.g., wetlands, 

lakes, reservoirs, etc.). 

Consequently, there is no evidence to suggest that construction of an additional electric 

transmission line within the existing transmission line corridor located south of the 

Gateway Substation in Kings County would result in increased avian mortality from line 

strikes.

Should you have any questions in regards to information presented in this technical 

memorandum please do not hesitate to contact me (916-638-7368). 

Sincerely, 

Michael Bumgardner 

Bumgardner Biological Consulting