Population models for social species: lessons learned from models of Red-cockaded Woodpeckers (Picoides borealis)

摘要

Behavior can have major impacts on the population dynamics of social species and should be incorporated into demographic models to realistically evaluate population trends and extinction risk. We compared the predictions of a stage- and age-based matrix model, an individual-based model (IBM, developed in the program Vortex), and a spatially explicit individual-based model (SEPM) with the actual dynamics of a population of Red-cockaded Woodpeckers (RCW; Picoides borealis) in the Sandhills of North Carolina, USA. Predictions, including population size, composition, and growth rate, differed the most from actual population characteristics for models that did not incorporate social structure. The SEPM most closely predicted actual population dynamics, underestimating the population by 2.3%. This model, specifically developed to simulate RCW population dynamics, contains many of the features that we assert are important for adequately incorporating social behavior into demographic and population modeling. These features include the ability to (1) differentiate individuals based on their stage class, (2) capture the dynamics of the population at both the individual and group level, (3) incorporate the positive or negative effects of subdominants, (4) include environmental and demographic stochasticity, and (5) capture dispersal and other spatial factors. The RCW SEPM, although currently species-specific, provides a strong blueprint for how population models for social species could be constructed in the future when data allow.