Importance of Power Pole Selection When Retrofitting for Eagle Compensatory Mitigation

Abstract

In the United States, the bald eagle Haliaeetus leucocephalus and golden eagle Aquila chrysaetos are managed by the U.S. Fish and Wildlife Service to ensure the species are stable or increasing while allowing for potentially negative effects from anthropogenic sources. Compensatory mitigation, through retrofitting high-risk power poles to reduce electrocutions, can be used to offset negative effects, enabling the U.S. Fish and Wildlife Service to achieve their management objectives of species stability and persistence. Regulators, permit holders, electric utilities, and consultants lack an objective and repeatable method for discriminating between high-risk and low-risk power poles. To illustrate the importance of accurately identifying and retrofitting high-risk poles, we compare conservation benefits among three retrofitting project scenarios: 1) high-risk poles only, 2) a circuit of both low- and high-risk poles, and 3) low-risk poles only. We assert that, in the absence of a common definition of high-risk power poles applied uniformly across the landscape, mitigation approved by the U.S. Fish and Wildlife Service could fall short of its intended value and be unable to meet management objectives. We define high-risk poles in the context of compensatory mitigation as poles in high-quality bald or golden eagle habitat with a relative risk index ≥ 0.40 based on number of phases, number of jumper wires, and presence of pole grounding. We estimate that the conservation benefit of retrofitting a high-risk pole is at least 5.25 times greater than the benefit of retrofitting a low-risk pole. In the long-term, if compensatory mitigation intended to achieve management objectives falls short of its assumed conservation value, the U.S. Fish and Wildlife Service could be forced to limit future permit authorizations until bald or golden eagles can recover from incorrectly calculated conservation benefits. To avoid that negative outcome, we recommend that the U.S. Fish and Wildlife Service set consistent and transparent standards for identifying poles to count as compensatory mitigation credit using our proposed definition of a high-risk power pole.