title: Uncertainty in Population Estimates for Endangered Animals and Improving the Recovery Process.
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.
authors.affiliation: Applied Conservation Lab, Department of Biology, Millersville University, Millersville, PA 17551, USA. Aaron.Haines@millersville.edu.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Haines
authors.affiliation: Applied Conservation Lab, Department of Biology, Millersville University, Millersville, PA 17551, USA. matthewmzak@gmail.com.
authors.forename: Matthew
authors.initials: M
authors.lastname: Zak
authors.affiliation: Ecology and Conservation Biology Program, College of Natural Resources, University of Idaho, Moscow, ID 83844, USA. brit0213@vandals.uidaho.edu.
authors.forename: Katie
authors.initials: K
authors.lastname: Hammond
authors.affiliation: Department of Fish and Wildlife Resources, College of Natural Resources, University of Idaho, Room 103, Moscow, ID 83844, USA. mscott@uidaho.edu.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Scott
authors.affiliation: College of Law, University of Idaho, Law 201, Moscow, ID 83844, USA. gobled@uidaho.edu.
authors.forename: Dale D
authors.initials: DD
authors.lastname: Goble
authors.affiliation: Department of Fish and Wildlife Resources, College of Natural Resources, University of Idaho, Room 103, Moscow, ID 83844, USA. jrachlow@uidaho.edu.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Rachlow
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 