Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, Tennessee, United States of America.
U.S. Geological Survey, Southern Appalachian Research Branch, Northern Rocky Mountain Science Center, University of Tennessee, Knoxville, Tennessee, United States of America.
PLoS One. 2018 Jan 23;13(1):e0191435. doi: 10.1371/journal.pone.0191435. eCollection 2018.
Monitoring vulnerable species is critical for their conservation. Thresholds or tipping points are commonly used to indicate when populations become vulnerable to extinction and to trigger changes in conservation actions. However, quantitative methods to determine such thresholds have not been well explored. The Louisiana black bear (Ursus americanus luteolus) was removed from the list of threatened and endangered species under the U.S. Endangered Species Act in 2016 and our objectives were to determine the most appropriate parameters and thresholds for monitoring and management action. Capture mark recapture (CMR) data from 2006 to 2012 were used to estimate population parameters and variances. We used stochastic population simulations and conditional classification trees to identify demographic rates for monitoring that would be most indicative of heighted extinction risk. We then identified thresholds that would be reliable predictors of population viability. Conditional classification trees indicated that annual apparent survival rates for adult females averaged over 5 years ([Formula: see text]) was the best predictor of population persistence. Specifically, population persistence was estimated to be ≥95% over 100 years when [Formula: see text], suggesting that this statistic can be used as threshold to trigger management intervention. Our evaluation produced monitoring protocols that reliably predicted population persistence and was cost-effective. We conclude that population projections and conditional classification trees can be valuable tools for identifying extinction thresholds used in monitoring programs.
监测脆弱物种对于它们的保护至关重要。阈值或临界点通常用于指示种群何时变得容易灭绝，并触发保护行动的改变。然而，用于确定这些阈值的定量方法尚未得到充分探索。路易斯安那黑熊（Ursus americanus luteolus）已于 2016 年从美国濒危物种法案的濒危和受威胁物种名单中移除，我们的目标是确定最适合监测和管理行动的参数和阈值。我们使用 2006 年至 2012 年的捕获标记再捕获（CMR）数据来估计种群参数和方差。我们使用随机种群模拟和条件分类树来确定最能指示灭绝风险增加的监测人口率。然后，我们确定了可作为种群生存能力可靠预测指标的阈值。条件分类树表明，成年雌性 5 年平均的年表观存活率（[公式：见正文]）是预测种群持久性的最佳指标。具体而言，当 [公式：见正文]时，种群的持久性估计在 100 年内将≥95%，表明该统计数据可用于作为触发管理干预的阈值。我们的评估产生了可靠预测种群持久性且具有成本效益的监测方案。我们得出结论，种群预测和条件分类树可以成为识别监测计划中灭绝阈值的有用工具。
