Effectively retrofitting powerlines to reduce raptor mortality

Abstract

Moon Lake Electric Association was sentenced to three years probation August 12, 1999 for electrocuting 17 eagles and hawks near Rangely, Colorado. The utility pleaded guilty to six violations of the Migratory Bird Treaty Act and the Eagle Protection Act. Under the settlement Moon Lake agreed to pay a $100000 fine and enter into a Memorandum of Understanding (MOU) with the US Fish and Wildlife Service. The MOU clarified utility obligations to protect birds and required a plan to prevent future bird deaths. This paper focuses on methods used to effectively retrofit Moon Lake's system. Over 3000 poles were inspected for raptor mortality. Prey remains were noted as well as habitat and prey abundance to determine preferred perches. Utility configurations associated with mortality were also recorded. These data were compiled to determine high-risk structures prioritized for immediate retrofitting. Deadend units and transformer banks were most problematic. Although many standard RUS-type three-phase tangent structures (RUS C1 Unit) lacked 60 inches of separation recommended by "Suggested Practices for Raptor Protection on Powerlines: The State of the Art in 1996" most were found to be safe. Existing retrofitting measures were also evaluated. The use of perch guards as a standard retrofitting measure was greatly reduced after guards contributed to several electrocutions. The use of bushing covers with small drain holes also created new electrocution problems with small birds probing bushing holes for insects. Guying and grounding practices also contributed to some bird mortality.