Assessing population viability while accounting for demographic and environmental uncertainty

Area of Science:

• Ecology
• Population Dynamics
• Conservation Biology

Background:

• Predicting population trends and viability is crucial in ecology.
• Environmental changes introduce uncertainty into population assessments, necessitating advanced modeling techniques.
• Traditional integrated population models often lack environmental uncertainty, limiting their predictive power.

Purpose of the Study:

• To incorporate environmental variation into integrated population models for more realistic population viability assessments.
• To estimate key demographic parameters, such as juvenile survival, which are difficult to measure empirically.
• To assess the past and future population trends of the Montserrat Oriole (Icterus oberi), a species threatened by volcanic activity.

Main Methods:

• Developed an integrated population model incorporating both demographic and environmental uncertainty.
• Applied the model to time series data of the Montserrat Oriole population.
• Estimated juvenile survival and population growth rates under varying environmental conditions.

Main Results:

• Montserrat Orioles showed reduced survival during volcanic ashfall years, countered by increased fecundity in high rainfall years.
• The model estimated a highly imprecise future population growth rate (95% credible interval 0.844-1.105) due to uncertainty.
• The probability of extinction for the Montserrat Oriole by 2028 was estimated to be low (2.1%).

Conclusions:

• Accounting for both demographic and environmental uncertainty provides a more realistic assessment of population viability.
• Integrated population models with environmental uncertainty are essential tools for conservation in unpredictable environments.
• The Montserrat Oriole's population dynamics are significantly influenced by volcanic activity and rainfall patterns.