A Coupled Human and Natural Systems Approach to Understanding an Invasive Frog, Eleutherodactylus Coqui, in Hawaii

Emily A. Kalnicky, Utah State University

This work made publicly available electronically on October 30, 2012.


Most ecosystems in the world have experienced some form of human impact. Global climate change, deforestation, and invasive species all affect the biodiversity of an area and, as a result of these human-driven impacts, ecosystems emerge that contain new species combinations previously undocumented. In order to better understand and manage these novel ecosystems, incorporating both social and natural components can be helpful. The overall objective of my research was to incorporate a coupled-systems approach to address social and biological factors affecting an invasive frog, Eleutherodactylus coqui, in Hawaii. Understanding these relationships allows suggestions to be made on potential management methods to control coqui populations, as well as more general suggestions for applying a similar approach to other novel ecosystem problems.

I conducted my research across the state of Hawaii. Specifically, the first research chapter focuses on research conducted across the island of Hawaii; the second on research conducted across the islands of Maui, Kauai, Oahu, and Hawaii; and the final chapter on research conducted in the Nanawale Forest Reserve (19°28’ N, 154°54’ W; elevation 230 m), in the southeast region of the island of Hawaii. Details for study locations can be found in each of the respective methods sections for these research chapters.

The first research chapter explores the coupled relationship between social and ecological variables and coqui frog abundance on private property by using both property-level surveys of natural variables and interviews of property owners. The second research chapter presents results from a quantitative study exploring the relationship between landowner attitudes, social influences, and coqui management behavior using a large mail survey. The final research chapter is an experimental examination of one of the most important ecological predictors for coqui success, habitat structure, and is broadly applicable to ecological research on the role of habitat structure in community dynamics.

Overall, I found that coqui density is affected by landowners’ attitudes and subsequent management behavior, but the frog’s density also influences these attitudes and behaviors. In this way, the success of the invasive coqui frog is part of a larger, coupled reciprocal system. Implications of the research, with a focus on placing the overall dissertation in the larger coupled social-natural research literature, are discussed in the final, conclusion chapter.