Print PageThe Gulf coastal ecosystems in Florida are foci of the highest species richness of imperiled shoreline dependent birds in the USA. However environmental and anthropogenic processes that affect their macroecological patterns, like occupancy and abundance, are not well unraveled. The Snowy Plover (Charadrius a. nivosus) is resident of northern and western Florida's white sandy estuarine/ocean beaches and is considered a state-threatened species. The Piping Plover (Charadrius melodus) and Red Knot (Calidris canutus) are migratory shorebirds that use the Florida Gulf beaches as wintering and stop-over areas respectively.
To quantify the apparent relationship between tropical cyclones and shorebird occurrences we used a Bayesian Monte Carlo procedure to sample from the posterior distribution of the binomial probabilities that a region was a breeding ground conditional on whether or not the previous year experienced a tropical cyclone. The Bayesian approach requires the data be neither uniform in precision nor the evidence complete. The approach provides a mathematical rule to update existing beliefs in light of new evidence.
Results/Conclusions
We show that the odds of Snowy Plover nesting in their suitable habitat during the spring following a tropical cyclone impact are seven times higher compared to the odds during the spring following a season without a cyclone. The results indicate also that it was 2.3, 3.1, and 0.8 times more likely that a region was not a wintering ground following a year with a renourishment intervention for the SP, PP and RK respectively. For the SP it was 2.5. times more likely that a region was not a breeding ground after a renourishment event.
Considering renourishment projects and shorebird we considered whether a region was not a nesting or a wintering ground conditional on the occurrence of a beach replenishment intervention in the same and the previous year. The feedbacks shorebirds-tropical cyclones and renourishments are imputable to a positive and negative widespread geomorphological restructuring of the beach habitat respectively. Considering climatological extremes, future climate scenario featuring fewer, but more extreme cyclones could result in a decrease in the breeding Snowy Plover population and its breeding range. Due to the similar geographic range and habitat suitability, and no decrease in abundance of other shorebirds in Florida after the cyclone season, our results suggest a common bioclimatic feedback for the other shorebirds. Bayesian analysis and modeling, in which uncertainties are quantified in terms of probability, offers an alternative approach to understanding in ecological applications.
