Master of Science (M.Sc.)
Identifying key factors of habitat quality and the extents at which they operate is invaluable to the understanding of the biology of a species. Key factors defining habitat quality for many common butterfly species have yet to be determined. Diverse methods are used to define habitat quality for butterflies. Some of these, such as mark-release-recapture or distance sampling, can be difficult to implement. Occupancy modeling is less invasive and generally less expensive than these other methods. Occupancy modeling is based on repeated presence-absence surveys. Occupancy is the probability that a species is present at a given site after accounting for imperfect detection. Detection is the probability that a species is detected given that it is present. The goal of this study was to identify factors at different spatial extents that are associated with occupancy, colonization (the probability that a site that was unoccupied in the previous time step is occupied in the current time step), and extinction (the probability that a site that was occupied in the previous time step is vacant in the current time step) of two common butterfly species in woodlands of the eastern United States, Eurytides marcellus and Papilio glaucus. For both species, the count and or proportion of host plants explained the greatest variation in occupancy. For E. marcellus, the greatest proportion of variation in probabilities of colonization and extinction was explained by the proportion of agricultural cover and the density of edges between forests and open-herbaceous areas and between forests and wetlands. The variables with which occupancy, colonization, and extinction of E. marcellus were most strongly associated were measured at extents from 90 m-5 km. Variables that explained the greatest variation in occupancy, colonization, and extinction of P. glaucus were measured over a smaller range of extents (540 m -3 km). Colonization was negatively associated with the proportion of open-herbaceous cover and the density of roads, suggesting that habitat quality for P. glaucus decreases as forest fragmentation increases. The proportion of wetland cover also had a consistent positive association with extinction of P. glaucus. This study suggests that colonization and extinction of P. glaucus and E. marcellus are associated with ecological processes and land use at extents of kilometers.
© The Author
Zappalla, Angela Louise, "Factors Affecting Temporal Variation in Occupancy of Two Common Species of Butterflies in Woodlands of the Eastern United States, Papilio Glaucus and Eurytides Marcellus." (2016). Dissertations, Theses, and Masters Projects. Paper 1477068027.