Simulating the Effects of Wetland Loss and Inter-Annual Variability on the Fitness of Migratory Bird Species

Long-distance migratory shorebirds require wetland stopover sites where they can forage and deposit sufficient fat to complete their migration and, in the spring, reproduce. Conservation biologists are concerned that continental-scale reductions in wetland availability and quality due to human disturbance, climate change, and natural drought events are negatively impacting these species by eliminating critical stopovers along migratory flyways. We describe an individual-based migration model driven by remotely sensed land surface data, climate data assimilation models, and biological field data to examine the impact of changing environmental conditions on migration routes, temporal patterns, and fitness. We used an evolutionary programming approach to evaluate birds´ adaptive responses to variation in refueling potential in the landscape. Birds´ shifted their migratory routes and extended their stopovers as the mean quality of the landscape decreased and spatial variation in refueling potential increased. We discuss possible applications of our model for understanding inter-annual climate variation, climate change, and wetland loss.