Uncertainty in Population Estimates for Endangered Animals and Improving the Recovery Process.

Aaron Haines,Janet Rachlow,Matthew Zak,Dale Goble,J Scott,Katie Hammond

doi:10.3390/ani3030745

Abstract

Simple SummaryThe objective of our study was to evaluate the mention of uncertainty (i.e., variance) associated with population size estimates within U.S. recovery plans for endangered animals. To do this we reviewed all finalized recovery plans for listed terrestrial vertebrate species. We found that more recent recovery plans reported more estimates of population size and uncertainty. Also, bird and mammal recovery plans reported more estimates of population size and uncertainty. We recommend that updated recovery plans combine uncertainty of population size estimates with a minimum detectable difference to aid in successful recovery. United States recovery plans contain biological information for a species listed under the Endangered Species Act and specify recovery criteria to provide basis for species recovery. The objective of our study was to evaluate whether recovery plans provide uncertainty (e.g., variance) with estimates of population size. We reviewed all finalized recovery plans for listed terrestrial vertebrate species to record the following data: (1) if a current population size was given, (2) if a measure of uncertainty or variance was associated with current estimates of population size and (3) if population size was stipulated for recovery. We found that 59% of completed recovery plans specified a current population size, 14.5% specified a variance for the current population size estimate and 43% specified population size as a recovery criterion. More recent recovery plans reported more estimates of current population size, uncertainty and population size as a recovery criterion. Also, bird and mammal recovery plans reported more estimates of population size and uncertainty compared to reptiles and amphibians. We suggest the use of calculating minimum detectable differences to improve confidence when delisting endangered animals and we identified incentives for individuals to get involved in recovery planning to improve access to quantitative data.

Highlights

In the United States, wildlife species of conservation concern are listed as either “endangered” or “threatened” depending on their status and probability of extinction as outlined within the EndangeredSpecies Act [1]
We found 59% of completed recovery plans specifying a current population size and 14.5% specifying a variance for the population size estimate
Of the recovery plans that stipulated a population size for delisting criteria, 20% reported a variance for the current population size

Summary

Introduction

In the United States, wildlife species of conservation concern are listed as either “endangered” or “threatened” depending on their status and probability of extinction as outlined within the EndangeredSpecies Act [1]. In the United States, wildlife species of conservation concern are listed as either “endangered” or “threatened” depending on their status and probability of extinction as outlined within the Endangered. The Endangered Species Act of 1973 [1] was created to provide a means by which endangered and threatened species and the ecosystems upon which they depend could be conserved Recovery plans contain all the available biological information for a listed species and specify the recovery criteria (a.k.a., recovery goals, recovery benchmarks, or recovery objectives) that (when achieved) will provide the basis for downlisting (i.e., reclassifying a species from endangered to threatened status) or delisting (i.e., removing a species from the protection of the ESA) [2]

Objectives

Results

Conclusion