Can an Avian Electrocution Risk Model From California Guide Retrofitting Throughout the Western United States?

Abstract

Abstract A previously published model of avian electrocution risk, the “2014 model,” compared power poles that electrocuted birds (electrocution poles; including 21 golden eagle Aquila chrysaetos electrocutions) with poles not known to have electrocuted birds (comparison poles). The 2014 model produces pole-specific risk index scores between 0 and 1. The scores rank relative risk so electric utilities can maximize conservation benefits per dollar spent by focusing retrofitting on poles with greatest risk. Although the creation of the 2014 model encompassed a study population of birds and poles in southern California, the 2014 model has potential for use in managing a target population of raptors including golden eagles throughout the western United States. Use beyond southern California is only appropriate if the study population is similar enough to the target population for the 2014 model to predict risk effectively. To evaluate similarity, we examined five sources of evidence: 1) the relative consistency in electrical safety codes for power poles; 2) the body sizes of golden eagles in the study and target populations; and consistency in structure-specific factors associated with 3) golden eagle electrocutions in other studies, 4) other avian electrocutions, and 5) previously unreported golden eagle electrocutions. We found that although the study population in the 2014 model included relatively few golden eagles, data were sufficient to create a model that is applicable to a target population throughout the western United States. The model also can be useful in helping determine equivalencies between pole types if utilities seek to compare benefits of retrofitting small numbers of high-risk poles with large numbers of low-risk poles.