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Animals 2013, 3(3), 745-753; doi:10.3390/ani3030745
Article

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

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Received: 1 July 2013; in revised form: 5 August 2013 / Accepted: 7 August 2013 / Published: 13 August 2013
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Abstract: 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.
Keywords: The 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. The 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.
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Haines, A.M.; Zak, M.; Hammond, K.; Scott, J.M.; Goble, D.D.; Rachlow, J.L. Uncertainty in Population Estimates for Endangered Animals and Improving the Recovery Process. Animals 2013, 3, 745-753.

AMA Style

Haines AM, Zak M, Hammond K, Scott JM, Goble DD, Rachlow JL. Uncertainty in Population Estimates for Endangered Animals and Improving the Recovery Process. Animals. 2013; 3(3):745-753.

Chicago/Turabian Style

Haines, Aaron M.; Zak, Matthew; Hammond, Katie; Scott, J. M.; Goble, Dale D.; Rachlow, Janet L. 2013. "Uncertainty in Population Estimates for Endangered Animals and Improving the Recovery Process." Animals 3, no. 3: 745-753.

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