Risk-Based Viable Population Monitoring

• Published in: Conservation biology Vol. 19; no. 6; pp. 1908 - 1916
• Main Authors: STAPLES, DAVID F., TAPER, MARK L., SHEPARD, BRADLEY B.
• Format: Journal Article
• Language: English
• Published: 350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK Blackwell Science Inc 01.12.2005; Blackwell Science; Blackwell; Blackwell Publishing Ltd
• Subjects: Animal populations; Animal, plant and microbial ecology; análisis de viabilidad poblacional; Applied ecology; AVP; Biological and medical sciences; Conservation biology; Conservation, protection and management of environment and wildlife; Depopulation; Endangered & extinct species; especies amenazadas y en peligro; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Geometric growth; Grizzly bears; Methods and techniques (sampling, tagging, trapping, modelling...); modelado de poblaciones; Modeling; Monitoring systems; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population dynamics; Population ecology; Population estimates; Population growth; population modeling; population viability analysis; PVA; recuperación de especies; Risk; Simulation; species recovery; threatened and endangered species; Trout; population modeling; Population survey; Endangered species; Restoration; Risk; PVA; population viability analysis; threatened and endangered species; species recovery; Modeling; Viability; Environmental protection
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1111/j.1523-1739.2005.00283.x

We describe risk-based viable population monitoring, in which the monitoring indicator is a yearly prediction of the probability that, within a given timeframe, the population abundance will decline below a prespecified level. Common abundance-based monitoring strategies usually have low power to detect declines in threatened and endangered species and are largely reactive to declines. Comparisons of the population's estimated risk of decline over time will help determine status in a more defensible manner than current monitoring methods. Monitoring risk is a more proactive approach; critical changes in the population's status are more likely to be demonstrated before a devastating decline than with abundance-based monitoring methods. In this framework, recovery is defined not as a single evaluation of long-term viability but as maintaining low risk of decline for the next several generations. Effects of errors in risk prediction techniques are mitigated through shorter prediction intervals, setting threshold abundances near current abundance, and explicitly incorporating uncertainty in risk estimates. Viable population monitoring also intrinsically adjusts monitoring effort relative to the population's true status and exhibits considerable robustness to model misspecification. We present simulations showing that risk predictions made with a simple exponential growth model can be effective monitoring indicators for population dynamics ranging from random walk to density dependence with stable, decreasing, or increasing equilibrium. In analyses of time-series data for five species, risk-based monitoring warned of future declines and demonstrated secure status more effectively than statistical tests for trend.