AN INDIVIDUAL-BASED, SPATIALLY-EXPLICIT SIMULATION-MODEL OF THE POPULATION-DYNAMICS OF THE ENDANGERED RED-COCKADED WOODPECKER, PICOIDES BOREALIS

Spatially-explicit population models allow a link between demography a nd the landscape. We developed a spatially-explicit simulation model f or the red-cockaded woodpecker, Picoides borealis, an endangered and t erritorial cooperative breeder endemic to the southeastern United Stat es. This kind of model is especially appropriate for this species beca use it can incorporate the spatial constraints on dispersal of helpers , and because territory locations are predictable. The model combines demographic data from a long-term study with a description of the spat ial location of territories. Sensitivity analysis of demographic param eters revealed that population stability was most sensitive to changes in female breeder mortality, mortality of female dispersers and the n umber of fledglings produced per brood. Population behavior was insens itive to initial stage distribution; reducing the initial number of bi rds by one-half had a negligible effect. Most importantly, we found th at the spatial distribution of territories had as strong an effect on response to demographic stochasticity as territory number. Populations were stable when territories were highly aggregated, with as few as 4 9 territories. When territories were highly dispersed, more than 169 t erritories were required to achieve stability. Model results indicate the importance of considering the spatial distribution of territories in management plans, and suggest that this approach is worthy of furth er development. (C) 1998 Elsevier Science Ltd. All rights reserved.