How do scientists estimate a species’ probability of extinction in the wild?

Scientists estimate a species' probability of extinction in the wild using several rigorous, science-based approaches that integrate demographic, geographic, and environmental data.

The IUCN Red List Criteria

The International Union for Conservation of Nature (IUCN) utilizes five quantitative criteria to assess extinction risk. Scientists evaluate a species based on:
* Population decline: The rate of reduction over the previous 10 years or three generations.12
* Geographic range: The extent of the area occupied or the degree of fragmentation.12
* Population size: The current number of mature individuals.12
* Restricted distribution: Whether the species lives in a very small or isolated area.12
* Quantitative analysis: Results from models that calculate the probability of extinction in the wild.12

Population Viability Analysis (PVA)

To provide more sophisticated estimates, researchers use population viability analysis (PVA). This computer simulation model incorporates a species' natural history—such as reproduction, dispersal behavior, and genetic context—to predict long-term persistence. PVA allows scientists to account for:3
* Stochasticity: Random environmental events (e.g., fires, droughts) and demographic fluctuations (e.g., birth/death rates, sex ratios).3
* Biological parameters: The impact of specific threats like habitat loss, disease, or inbreeding.3

By identifying the minimum viable population (MVP) required for survival, scientists can set quantitative targets for conservation management.3