Biological and Sociopolitical Sources of Uncertainty in Population Viability Analysis for Endangered Species Recovery Planning

Carlos Carroll,Daniel J Rohlf,Richard J Fredrickson,Robert C Lacy,Michael K Phillips,Sarah A Hendricks

doi:10.1038/s41598-019-45032-2

Abstract

Although population viability analysis (PVA) can be an important tool for strengthening endangered species recovery efforts, the extent to which such analyses remain embedded in the social process of recovery planning is often unrecognized. We analyzed two recovery plans for the Mexican wolf that were developed using similar data and methods but arrived at contrasting conclusions as to appropriate recovery goals or criteria. We found that approximately half of the contrast arose from uncertainty regarding biological data, with the remainder divided between policy-related decisions and mixed biological-policy factors. Contrasts arose from both differences in input parameter values and how parameter uncertainty informed the level of precaution embodied in resulting criteria. Policy-related uncertainty originated from contrasts in thresholds for acceptable risk and disagreement as to how to define endangered species recovery. Rather than turning to PVA to produce politically acceptable definitions of recovery that appear science-based, agencies should clarify the nexus between science and policy elements in their decision processes. The limitations we identify in endangered-species policy and how PVAs are conducted as part of recovery planning must be addressed if PVAs are to fulfill their potential to increase the odds of successful conservation outcomes.

Highlights

The Mexican wolf (C. l. baileyi), which historically occurred in northern Mexico and the southwestern US, was extirpated from the wild by the 1980s due to such conflicts[5]
This biological uncertainty in turn can be distinguished from policy‐based uncertainty, which originates from the social process of recovery planning and cannot be reduced by gathering additional data on the species of concern
Our results indicate that about half (40–46%, depending on which population viability analysis (PVA) output metric was considered) of explained contrast between the 2013 and 2017 Mexican wolf recovery criteria was attributed to two parameters we categorized as biological (Fig. 1)

Summary

Introduction

The Mexican wolf (C. l. baileyi), which historically occurred in northern Mexico and the southwestern US, was extirpated from the wild by the 1980s due to such conflicts[5]. In 2013, a team of scientists convened by the Service employed PVA to develop draft Mexican wolf recovery criteria[8] These criteria, which were shelved after generating opposition from prominent politicians in southwestern US states[9], proposed that a metapopulation totaling 750 wolves within the US would be necessary for recovery of the subspecies[8,10]. We propose methods to address identified sources of uncertainty (both biological and sociopolitical) and strengthen the utility of PVA in recovery planning The lessons from this comparison resonate beyond the US context, for example in the controversy over the appropriate size of the Swedish wolf population[11,12], because they highlight key aspects of the conceptual framework underpinning endangered species recovery that remain contested and present pitfalls to successful recovery planning in many nations

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Conclusion