Modeling impacts of landscape connectivity on dispersal movements of northern flying squirrels (Glaucomys sabrinus griseifrons)

Abstract

Landscape connectivity is a key component for successful dispersal of wildlife. Many approaches to quantify landscape connectivity utilize landscape characteristics and wildlife behavior in response to those characteristics, whereas other approaches focus on wildlife dispersal behavior. Combining landscape structure and wildlife behavior (e.g. movement, food acquisition, response to predation risk) provides critical information for conservation and management of many species. Individual-based models (IBM) are useful tools for evaluating the interaction between landscape characteristics and individual behaviors, thereby providing insights into management and conservation. Our objective was to evaluate the effect of reductions in landscape connectivity on northern flying squirrel dispersal movements under alternative timber management scenarios within the modeling framework of a spatially-explicit IBM. We simulated timber harvests of 6% and 9% of old-growth forest, the primary habitat for this species, distributed across 5, 10 or 15 harvest locations. We measured the influence of these scenarios upon landscape connectivity for flying squirrels. Landscapes with greater connectivity exhibited longer flying squirrel dispersal distances, more sinuous dispersal paths, and a greater total area of landscape utilization. However, connectivity was not directly correlated with habitat loss. The harvest scenario with 6% harvest of old growth distributed among 15 harvest locations had the lowest connectivity index value despite other scenarios modeling a greater percentage of old growth loss. The IBM demonstrated the importance of behaviors such as path tortuosity and movement rates in conjunction with landscape configuration in influencing the movement of dispersing individuals. The spatially explicit IBM provided a framework to evaluate connectivity from a fine-scale behavioral rather than structural perspective as well as to evaluate the distribution of new home range locations, which could be a useful management tool when evaluating the influence of landscape heterogeneity and stochastic behavior on wildlife movement and dispersal.