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Updated Collision Risk Model Priors for Estimating Eagle Fatalities at Wind Energy Facilities

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Fish and Wildlife Service, Interior.


Reopening of the comment period.


The U.S. Fish and Wildlife Service (Service) uses a collision risk model (CRM) to predict the number of golden and bald eagles that may be killed at new wind facilities. The model incorporates existing information on eagle exposure and collision probability in the form of prior distributions (priors). The Service has updated the priors for both species of eagle and, on June 21 of this year, announced the availability of a report of the analysis conducted to generate the new priors (83 FR 28858). The notice solicited public comments on how the Service should use the new bald eagle priors. Today's notice reopens the comment period for 30 days, and provides additional information requested by commenters.


To ensure consideration of written comments, they must be submitted on or before December 13, 2018.


You may submit written comments by one of the following methods:

Electronically: Go to the Federal e-Rulemaking Portal: Search for FWS-HQ-MB-2017-0092, which is the docket number for this notice, and follow the directions for submitting comments.

By hard copy: Submit by U.S. mail or hand-delivery to Public Comments Processing, Attn: FWS-HQ-MB-2017-0092; Division of Policy, Performance, and Management Programs; U.S. Fish and Wildlife Service; MS: BPHC; 5275 Leesburg Pike, Falls Church, VA 22041-3803.

We will post all comments on This generally Start Printed Page 56366means that we will post any personal information you provide us (see Request for Information below for more information).

We request that you send comments by only one of the methods described above. We will post all information received on This generally means that we will post any personal information you provide us (see the Public Availability of Comments section below for more information).

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Ken Richkus, at 703-358-1780 (telephone), or (email). Individuals who are hearing impaired or speech impaired may call the Federal Relay Service at 800-877-8337 for TTY assistance.

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The U.S. Fish and Wildlife Service (Service) uses a collision risk model (CRM) to predict the number of golden and bald eagles that may be killed at new wind facilities (USFWS 2013; New et al. 2015). The CRM incorporates existing knowledge of eagle use around a proposed wind facility (exposure) and the probability of an eagle colliding with an operating turbine (collision probability).

The CRM is constructed using a Bayesian framework, and as such incorporates existing information on eagle exposure and collision probability in the form of prior distributions (priors). The priors are formally combined with site-specific data on exposure and the amount of hazardous area and operational time for a site to estimate the expected number of annual eagle collision fatalities.

The Service recently updated the priors for both species of eagle using all available data that meet specific criteria, substantially more data than were available when the original priors were established. We released a report of the analysis undertaken to generate the updated priors and announced the availability of the report in a June 21, 2018, Federal Register notice published on (83 FR 28858). In that notice we asked for public input on options for how we should apply the new bald eagle priors. Several of the comments we received during the initial comment period requested that the Service provide the values for the shape and rate parameters of the gamma and beta distributions described in the referenced report. In response to these comments, we have posted an updated version of the report that provides those parameter values on the Service's website at:​birds/​management/​managedspecies/​eaglemanagement.php. You can also find the report on the Federal e-Rulemaking Portal: Search for FWS-HQ-MB-2017-0092.

Because the bald eagle collision prior is based on data from only 14 sites that do not span the range of bald eagle density conditions that exist across the country, the prior may not be as representative as it would be if data from a wider range of location had been available. Given this uncertainty, the Service is considering three alternatives for how to incorporate species-specific priors for bald eagles into the CRM and fatality modeling process:

(1) Use the updated species-specific priors, and use the 80th quantile of the CRM fatality estimates as the initial permitted take number for permits, as is the current practice.

(2) Use the updated species-specific priors, but because the status of bald eagles is secure, adopt a risk-tolerant policy for bald eagles and select a more liberal quantile on the CRM fatality distribution as the initial permitted take number for this species.

(3) Given the limitations in data available to inform the bald eagle priors, initiate an expert elicitation process to further refine the bald eagle priors.

Under any of these scenarios, the Service would use data submitted under permits to make updates to the priors in the future.

Alternative 1 would mean that for a similar level of eagle use observed at a project site, the Service would use higher fatality estimates for bald eagles than for golden eagles. Alternative 2 would be a decision by the Service to be more `risk-tolerant' for bald eagles. This would mean that initial fatality predictions would be lower, however it would also likely mean that more permits would have to be amended to increase the permitted take over time (i.e., the Service would be underestimating take more often). Alternative 3 would be a decision by the Service that more information is needed to understand the potential variability of exposure and collision probability for bald eagles. Such a process could result in either higher or lower (or more variable) priors. We are soliciting input from the public on these three alternatives. We are not seeking input on the CRM itself, which has been peer-reviewed and been the subject of multiple rounds of public comment in the past.

Public Availability of Comments

Written comments we receive become part of the public record associated with this action. Before including your address, phone number, email address, or other personal identifying information in your comment, you should be aware that the entire comment—including your personal identifying information—may be made publicly available at any time. While you can ask us in your comment to withhold your personal identifying information from public review, we cannot guarantee that we will be able to do so. All submissions from organizations or businesses, and from individuals identifying themselves as representatives or officials of organizations or businesses, will be made available for public disclosure in their entirety.

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Dated: October 29, 2018.

Andrea Travnicek,

Principal Deputy Assistant Secretary, Water and Science, Exercising the authority of the Assistant Secretary for Fish and Wildlife and Parks.

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[FR Doc. 2018-24718 Filed 11-9-18; 8:45 am]