Population Viability Analysis Calculator

Population Viability Analysis is a quantitative method used to assess the risk of extinction for wildlife populations. It uses demographic data and environmental factors to predict the probability that a population will persist over a specified time period.

Extinction probability represents the likelihood that a population will fall below the extinction threshold within the specified time horizon. A probability above 10% is generally considered high risk for conservation purposes.

Environmental variance accounts for year-to-year fluctuations in conditions like weather, food availability, or habitat quality. Higher environmental variance increases extinction risk by causing more unpredictable population fluctuations.

Demographic stochasticity refers to random variation in births, deaths, and reproduction that occurs even in constant environments. It has a stronger effect on smaller populations and can push them toward extinction.

Carrying capacity should reflect the maximum number of individuals the habitat can sustain. Consider factors like available territory, food resources, and breeding sites. It's often estimated from historical population peaks or habitat assessments.

The extinction threshold is typically set between 1-10 individuals, representing the minimum viable population size. Very small populations face high extinction risk due to inbreeding, genetic drift, and demographic stochasticity.

More simulations provide more reliable estimates. 1,000 simulations are usually sufficient for most analyses, while 10,000 provide greater precision for critical conservation decisions or research publications.

Lambda is the finite rate of population increase. Values less than 1 indicate population decline, while values greater than 1 indicate growth. It's calculated as the exponential of the intrinsic growth rate (λ = e^r).