Name: Population Viability Analysis

Reference: Beissinger, S.R. and McCullough, D.R. (2002). Population Viability Analysis. University of Chicago Press, Chicago, Illinois.

Source: Various “enabling tools” are available for PVA. The one most widely used by CBSG is Vortex, available from: http://www.vortex10.org/Index.aspx

See also RAMAS - http://www.cbsg.org/ramas-software-population-modeling

Conservation planning step(s) when this would be used: PVA can be used during the Review Status step, to evaluate extinction risk and to assess the relative importance of threats. It can be used during the Plan Actions step to evaluate the relative efficacy of different potential management interventions and to identify key parameters for monitoring, and during the Evaluate and Adapt step where new data from monitoring are used to evaluate progress.

Description of tool use: Using specialized software, computerized simulation models of the focal species are constructed, based on current understanding of the species’ biology and of the external factors impacting on it. These models can then be used to predict the future status of the population or populations under study.

For example, models can provide insights into immediate and future extinction risk under existing conditions. They can be used to: assess the relative contribution of identified threats to observed population declines; to evaluate the relative impact of different management interventions on population recovery; and to identify those aspects of a species’ life-history that have the greatest impact on population health, to assist the design of monitoring programs.

Experience and expertise required to use the tool: Specialized expertise is required to apply these tools appropriately and responsibly.

Data requirements: This can vary depending on the application. Where the questions asked of the models require specific, quantitative answers, the data on which the models are based must be sound, complete, and reliable. For more general questions and comparative studies those requirements may be relaxed. Specialist advice should be sought to ensure that the data are sufficient for the required application.

Cost: The Vortex software is FREE for non-commercial applications. The costs of other programs can vary considerably based on degree of complexity and sophistication. The cost of the required expertise to build and interpret the models will also vary and may be significant.

Strengths and weaknesses, when to use and interpret with caution: See above. If not interpreted properly, model outputs may encourage confidence in results not warranted given the data on which they are based. Specialist advice should be sought.

Case study:
Miller, P.S. 2006. Population Viability Analysis for the Greater Sage Grouse (Centrocercus urophasianus) in Colorado. Apple Valley, MN: IUCN/SSC Conservation Breeding Specialist Group.

Back to Abruzzi Table 1.
___________________________________________________________________________
Contributor(s): Phil Miller            
Affiliation: CBSG
Email: pmiller@cbsg.org
Date: January 17, 2012