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Data Series 729

Fatality Estimator User’s Guide

By Manuela Huso, Nicholas Som, and Lew Ladd


This publication is the User's Guide for software developed to estimate wildlife fatalities at wind-power facilities, although the software is applicable to a variety of circumstances in which the objective is to estimate the size of a superpopulation and the probability of detection of the individuals is less than one. Simple counts of carcasses do not accurately reflect fatality and do not allow comparison among locations because carcasses may be detected at different rates. This software uses data collected during carcass searches and knowledge of detection rates to accurately estimate the number of fatalities and to provide a measure of precision associated with the estimate. These estimates are fundamental to understanding acute and cumulative effects of wind power on wildlife populations.

Only carcasses judged to have been killed after the previous search should be included in the fatality data set submitted to this estimator software. This estimator already corrects for carcasses missed in previous searches, so carcasses judged to have been missed at least once should be considered “incidental” and not included in the fatality data set used to estimate fatality. Note: When observed carcass count is <5 (including 0 for species known to be at risk, but not observed), USGS Data Series 881 ( is recommended for fatality estimation.

First posted December 11, 2012

Revised December 10, 2018

For additional information contact:
Director, Forest and Rangeland Ecosystem Science Center,
U.S. Geological Survey, 777 NW 9th Street
Corvallis, Oregon 97330

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Huso, Manuela, Som, Nicholas, and Ladd, Lew, 2018, Fatality estimator user’s guide (ver. 1.2, December 2018): U.S. Geological Survey Data Series 729, 22 p.,




Getting Started

Main Page



References Cited

Appendix A. Flow Chart of Estimation Process and Bootstrap Variance

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