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Raptor Electrocution Research
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 Electrocution on power lines is one of many human-caused mortality factors that may limit raptor populations. The Snake River Field Station has been involved in raptor electrocution issues since 1996 when it cooperated with the electric industry and the Raptor Research Foundation to develop a handbook on preventing raptor electrocutions. In 1999, the Station also began an assessment of raptor electrocution mortality in the Snake River Birds of Prey National Conservation Area (NCA) in southwestern Idaho.
Suggested Practices for Raptor Protection on Power Lines: the State of the Art in 1996
Suggested Practices for Raptor Protection on Power Lines has served as the industry standard for construction of raptor-safe power lines in the United States for over 25 years. It is the result of 3 decades of research on the raptor electrocution problem. Early findings and recommendations were summarized in the first edition, published in 1975. This was followed by a second edition, published in 1981. Fifteen years of additional experience and research was summarized in a third edition, published in 1996 by the Edison Electric Institute, Avian Power Line Interaction Committee, and Raptor Research Foundation. The third edition incorporates and builds from material in the previous editions, but represents a major update and revision. It offers the reader an expanded range of solutions to hazardous power line designs recognized since the 1970's, and to hazardous designs identified since the last edition was published in 1981. The third edition is presently being reprinted and will be available sometime early in 2000. For ordering information contact 1-800-334-5453.
Raptor Electrocution Issues in the NCA
The NCA, located about 45 minutes south of Boise, supports one of the highest densities of cliff-nesting raptors in the world. One of the most important management issues in the NCA is the conversion of native shrub habitats to non-native annual grasslands due to wildfires. A separate but related issue in the NCA is electrocution of raptors on power lines. Habitat conversions and raptor electrocutions are linked because electrocuted birds are a possible source of fire ignitions.
Currently, little is known about electrocution risks in the NCA. What is known is that electrocution of large birds including, raptors, common ravens, and great blue herons have resulted in at least 26 fire starts in and near the NCA since 1976. One of these, the 3,700-ha Sinker Butte Fire, destroyed a significant portion of the NCA's remaining shrublands in 1996. Recent studies indicate that habitat conversions due to wildfires, in combination with other disturbances, are having serious effects on some raptor species in the NCA. The golden eagle and prairie falcon, in particular, have experienced significant population declines in recent years.  In 1999, SRFS began a study to assess raptor electrocution rates and identify electrocution hazards in and near the NCA. Eventually, this will allow the Idaho Power Company to develop a program for reducing both power line-related mortalities and fire hazards.
In 1999, we produced a distribution line map of the study area, selected study segments, and began searching for dead raptors along 19 segments totaling 61.2 linear km. Study segments are located in the relatively undeveloped interior of the NCA, and along the borders and private inholdings of the NCA where agriculture and associated power line developments are common. From September-December, we visited all study segments twice and found the remains of 24 dead birds. We were able to identify 6 Common Ravens (Corvus corax), 2 Red-tailed Hawks (Buteo jamaicensis), 2 American Kestrels (Falco sparverius), 1 Northern Harrier (Circus cyaneus), 1 Golden Eagle (Aquila chrysaetos), and 1 Barn Owl (Tyto alba). Only the Golden Eagle showed clear signs of electrocution, but most remains were too old to establish cause of death. Some of the birds almost certainly were shot. Our intent in 2000 is to continue sampling study segments each month until a full year of sampling has been completed. This will allow detection of seasonal differences in mortality during 3 raptor concentration periods--nesting, postfledging, and wintering.
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