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SUGGESTED PRACTICES FOR RAPTOR PROTECTION ON POWERLINES
<br /> • In early 1972, a group of western utilitiesl with the assistance of the Edison Electric Institute, coordinated
<br /> a workshop with various Federal and State agencies and other interested groups2 to study the problems associated with
<br /> raptor electrocution occurring on powerlines. It was determined that grounding practices on distribution and trans-
<br /> mission lines from 4 k V through 69 kV along with certain configurations of transformer banks,fused cutouts,lightning
<br /> arresters and conductor phase spacings could be a substantial cause of raptor deaths. Subsequent studies have proved
<br /> that the solution to the problem lies more with engineering expertise than with a biological approach.
<br /> The electrocution problem appears to be greater in the western United States — primarily Colorado, Idaho,
<br /> Nevada, Utah and Wyoming—because the eagle population is greater there. Recent studies also document electrocution
<br /> losses of egrets, herons, crows, ravens, wild turkeys and other birds of prey, but current evidence shows that 90% of
<br /> all electrocution victims are golden eagles. This loss of eagles is significant;but pesticide contaminations,loss of habitat,
<br /> and illegal shooting remain the most threatening problems to raptors in general. The latter two mortality factors, which
<br /> lead directly from land use patterns and irresponsible use of firearms, are of particular importance to eagle
<br /> conservation.
<br /> The Department of the Interior has coordinated the counting of eagle electrocutions in the United States in
<br /> cooperation with the electric utility industry and various State and private conservation agencies.Since initiation of this
<br /> program, approximately 500 raptors,principally golden eagles, have been found at the base of power poles.A number
<br /> of these deaths can be attributed to other causes including diseases,poisoning and irresponsible use of firearms. The
<br /> count also showed 98% of the eagles electrocuted were young, inexperienced golden eagles that were just learning to
<br /> fly. They had not yet attained the skill and precision necessary to negotiate a safe landing or take-off from a powerline
<br /> pole supporting three or more conductors, transformer banks, fused cutouts or other equipment necessary to transmit
<br /> or distribute electric energy.
<br /> To deal with the factors that contribute to raptor electrocutions, it is necessary to know some things about the
<br /> birds: how they hunt, where they live and nest, and their art of flying. Eagles and hawks prefer to perch on elevated
<br /> sites where prey species might be observed over a wide radius and where air currents are more favorable for flight.
<br /> The preferred power pole perch, for instance, is more often one where the crossarm is perpendicular to the prevailing
<br /> wind and commands considerable hunting territory. The use of_powerline poles as perch sites varies according to .
<br /> topography, season and abundance of prey, powerlines that traverse steep and broken terrain, where many natural
<br /> 'peiCh"sites are avaiAble;receive little use compare o oin�se broad valleys where natural perch sites are absent.
<br /> • `7Nos�ectroccutiuns talrc�ce�nng t e winienng period when peak populations of eagles and hawks are present.At
<br /> this time, resident birds, as well as migrants, tend to concentrate in mountain valleys,adjacent foothills and grasslands
<br /> where food supplies are most abundant and available. During this period,powerline poles receive heavy use as perches,
<br /> as evidenced by droppings on crossarms and castings beneath the poles. Losses may be expected if lines in these areas
<br /> are not properly designed or modified.
<br /> Through the efforts of many, including Dr. Richard R. Olendorff, Bureau of Land Management (BLM),
<br /> Washington, D. C., Mr. Erwin L. Boeker, U. S. Fish & Wildlife Service, Denver, Colorado, and Mr. Morlan W. Nelson,
<br /> recognized authority on birds of prey and Birds-of--Prey Consultant to the Idaho Power Company, more has become
<br /> known about the eagle's habits and habitats. This information has been used by the electric utility industry to pinpoint
<br /> and then minimize or eliminate the problem through design changes on certain portions of existing, as well as future,
<br /> lines.
<br /> On March 27, 1972, the Rural Electrification Administration (REA) issued Bulletin 61-10 which was titled
<br /> 'Protection of Bald and Golden Eagles from Powerlines': This bulletin dealt with the causes of raptor electrocutions
<br /> from certain grounding practices that made it difficult for large birds of prey to fly away from or roost on powerline
<br /> poles or appurtenances without simultaneously contacting an energized conductor and a ground, thereby causing a
<br /> completed circuit and electrocution. With this bulletin,the REA specified that all cooperatives would change grounding
<br /> and construction practices to eliminate the possibility of electrocution. Some of the suggested designs,alterations and
<br /> additions of special perches can be seen in Exhibits 1 through 4 in the Appendix. Suggestions for increasing phase
<br /> spacings on pre-1962 standard construction were included.Exhibit No.2 shows that pole ground wires could be gapped
<br /> and still provide lightning protection to the powerline. This procedure eliminates a positive ground during normal
<br /> operation of the line, thus minimizing the possibility of simultaneous contact between an energized conductor and
<br /> ground. It was not intended that all existing lines be altered,but it was implied that preferred poles would be modified
<br /> when multiple electrocutions at specific locations could be documented and proved.
<br /> 1 Idaho Power Company, Pacific Gas& Electric Company,Pacific Power& Light Company,Public Service Company
<br /> of Colorado, Tucson Gas& Electric,Utah Power&Light Company.
<br /> • 2 Colorado Division of Wildlife,National Audubon Society,National Wildlife Federation,Rural Electrification
<br /> Administration,U. S.Fish and Wildlife Service.
<br /> — 1—
<br /> June 1995.
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