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MONITORING DECLINING METAPOPULATIONS: INSIGHTS FROM A MODEL SIMULATION
Citation:
Trenham, P. C. AND C. Ray. MONITORING DECLINING METAPOPULATIONS: INSIGHTS FROM A MODEL SIMULATION. Presented at 62nd Midwest Fish and Wildlife Conference, Minneapolis, MN, December 3-6, 2000.
Description:
Pond-breeding amphibians, host-specialist butterflies, and a variety of other organisms have been shown to exhibit population structures and dynamics consistent with metapopulation theory. In recent years large-scale biodiversity monitoring efforts have been initiated in many regions with the primary goal of detecting large-scale declines. The analysis of these monitoring data typically assumes that all sites are equivalntly suitable and independent. However, if these animals are organized as regional metapopulations, analysis and/or monitoring approaches based on this theory may be better suited to detect declines rapidly. We created a stochastic patch occupancy metapopulation model and used this model to test the ability of variations on standard route regression (RR) analysis to correctly diagnose metapopulation declines of varying magnitude. The variations that we used were: 1) standard RR; 2) RR with sites weighted based on the number of habitat patches within 10 map units; and 3) RR with sites weighted based on the number and location of habitat patches within 10 map units. Our results indicate that, given a system with metapopulation structure/dynamics, simple introducing the density of habitat patches around each survey point into the analyses can dramatically reduce the time required to detect statistically significant declines. Assuming that the target species has a metapopulation structure and that habitat patches suitable for its use can be identified from maps or GIS layers, our model suggests that we may be able to improve our ability to detect declines within existing monitoring designs.