A habitat-based population model for the Great Lakes population of the piping plover ( Charadrius melodus)

We created a stochastic habitat-based population model to compare the relative effectiveness of potential conservation strategies to increase the endangered Great Lakes population of piping plovers. Initial model parameters were based on an extensive 14-year dataset obtained by annual studies of breeding pairs in Michigan and 6 years of observations of color-marked individuals. Cumulative persistence probability curves and population trends were compared for scenarios with all possible combinations of the following: (1) empirical, medium and high site specific probabilities of reproductive success and (2) empirical, medium and high numbers of available breeding territories. Sites were also categorized according to land ownership to determine if long-term preservation of publicly owned lands is sufficient for population recovery under any of the scenarios. Only scenarios in which both reproduction and habitat availability were high and all ownership classes were included resulted in a model population that persisted for 100 years and was likely to reach the US Fish and Wildlife Service current population recovery goal (100 breeding pairs) for Michigan. The model was most sensitive to survival rates of adults and more sensitive to changes in reproductive parameters than to number of breeding sites or territories. Model results suggest that intensive measures to increase productivity alone are not sufficient for population recovery; increases in nesting densities or total number of available territories are also likely necessary. Given uncertainties about nesting densities possible at specific breeding sites, preservation of presently unoccupied habitat throughout the Great Lakes region and management of this habitat to encourage breeding by plovers are recommended. Use of techniques to augment the breeding population in conjunction with protection of habitat and reproduction may be warranted.