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Evaluation of Two Approaches to Defining Extinction Risk under the U.S. Endangered Species Act.

Publication ,  Journal Article
Thompson, GG; Maguire, LA; Regan, TJ
Published in: Risk analysis : an official publication of the Society for Risk Analysis
May 2018

The predominant definition of extinction risk in conservation biology involves evaluating the cumulative distribution function (CDF) of extinction time at a particular point (the "time horizon"). Using the principles of decision theory, this article develops an alternative definition of extinction risk as the expected loss (EL) to society resulting from eventual extinction of a species. Distinct roles are identified for time preference and risk aversion. Ranges of tentative values for the parameters of the two approaches are proposed, and the performances of the two approaches are compared and contrasted for a small set of real-world species with published extinction time distributions and a large set of hypothetical extinction time distributions. Potential issues with each approach are evaluated, and the EL approach is recommended as the better of the two. The CDF approach suffers from the fact that extinctions that occur at any time before the specified time horizon are weighted equally, while extinctions that occur beyond the specified time horizon receive no weight at all. It also suffers from the fact that the time horizon does not correspond to any natural phenomenon, and so is impossible to specify nonarbitrarily; yet the results can depend critically on the specified value. In contrast, the EL approach has the advantage of weighting extinction time continuously, with no artificial time horizon, and the parameters of the approach (the rates of time preference and risk aversion) do correspond to natural phenomena, and so can be specified nonarbitrarily.

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Published In

Risk analysis : an official publication of the Society for Risk Analysis

DOI

EISSN

1539-6924

ISSN

0272-4332

Publication Date

May 2018

Volume

38

Issue

5

Start / End Page

1009 / 1035

Related Subject Headings

  • Strategic, Defence & Security Studies
 

Citation

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Chicago
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Thompson, G. G., Maguire, L. A., & Regan, T. J. (2018). Evaluation of Two Approaches to Defining Extinction Risk under the U.S. Endangered Species Act. Risk Analysis : An Official Publication of the Society for Risk Analysis, 38(5), 1009–1035. https://doi.org/10.1111/risa.12927
Thompson, Grant G., Lynn A. Maguire, and Tracey J. Regan. “Evaluation of Two Approaches to Defining Extinction Risk under the U.S. Endangered Species Act.Risk Analysis : An Official Publication of the Society for Risk Analysis 38, no. 5 (May 2018): 1009–35. https://doi.org/10.1111/risa.12927.
Thompson GG, Maguire LA, Regan TJ. Evaluation of Two Approaches to Defining Extinction Risk under the U.S. Endangered Species Act. Risk analysis : an official publication of the Society for Risk Analysis. 2018 May;38(5):1009–35.
Thompson, Grant G., et al. “Evaluation of Two Approaches to Defining Extinction Risk under the U.S. Endangered Species Act.Risk Analysis : An Official Publication of the Society for Risk Analysis, vol. 38, no. 5, May 2018, pp. 1009–35. Epmc, doi:10.1111/risa.12927.
Thompson GG, Maguire LA, Regan TJ. Evaluation of Two Approaches to Defining Extinction Risk under the U.S. Endangered Species Act. Risk analysis : an official publication of the Society for Risk Analysis. 2018 May;38(5):1009–1035.
Journal cover image

Published In

Risk analysis : an official publication of the Society for Risk Analysis

DOI

EISSN

1539-6924

ISSN

0272-4332

Publication Date

May 2018

Volume

38

Issue

5

Start / End Page

1009 / 1035

Related Subject Headings

  • Strategic, Defence & Security Studies