Long-term population dynamics of an endangered butterfly are influenced by hurricane-mediated disturbance

Abstract

Effective species conservation requires understanding an organisms population dynamics and natural history, but long-term data are challenging to collect and maintain. As a result, conservation management decisions are frequently made using short-term data, which are insufficient to accurately assess population trends in most species. For less-studied taxa, including most invertebrates, inadequate understanding of life and natural history also impedes conservation efforts. Long-term studies are highly valuable for improving conservation decisions for target species as they serve as a model for other understudied species. We use mark-recapture data collected over 35 years to examine weather drivers of population patterns for an endangered butterfly, Schaus swallowtail (Heraclides ponceana), and to enhance our understanding of its natural history. We show that the population size of Schaus swallowtail butterfly was highly variable, ranging from under 100 to over 10,000 individuals. Population size is influenced by weather events and population size in the previous year. Population size was lower immediately following high wind events but was positively influenced by high wind events four years prior, with notable population increases following tropical cyclone events. Precipitation during the dry season preceding the adult flight period was also associated with higher population sizes. This study reveals the potentially beneficial role of hurricane-mediated disturbance on Schaus swallowtail populations potentially due to increased treefall gaps and the resulting shifts in plant communities. This remarkable data set represents one of the longest-term studies on a tropical insect.