College - Author 1
College of Science and Mathematics
Department - Author 1
Biological Sciences Department
Degree Name - Author 1
BS in Biological Sciences
Francis Villablanca, College of Science and Mathematics, Biological Sciences Department
Western monarch butterflies (sp. Danaus plexippus) are undergoing a severe decline that rivals those occurring among insects across the globe. Despite the estimation of population abundance, growth rates, and extinction probabilities, no analyses have investigated spatiotemporal patterns of decline in the western monarch population. I performed occupancy modeling of Western Monarch Thanksgiving Count (WMTC) data. The data was constrained spatially and temporally, with sites grouped into occupancy bins by latitude and year. Occupancy probabilities (psi) were estimated for each intersection of a latitude and time bin and detection probabilities (p) were estimated for each time bin. Psi increased slightly and non-significantly from northern to southern latitude bins. However, the dataset was unable to support any models with >3 latitude bins or the intersection of latitude and time bins because the dataset contained unequal sampling distributions across both space and time and a high proportion of missing observations. These constraints are likely driven by the reliance upon citizen science for WMTC data collection, and thus those constraints may be present in other citizen science datasets. Despite inconclusion regarding my original research questions, I concluded that occupancy modeling requires robust datasets that are more complete and equally distributed across the relevant parameters than the WMTC data. As species begin to decline, datasets with these characteristics may be harder to generate, suggesting that occupancy modeling may not be suitable for western monarch butterflies or other insect populations in the future.