Another major component of my PhD work is to examine regional changes in Odonata communties and species distribution using information from museum collections. In collaboration with Calbug (an NSF-funded effort to digitize entomology collections in California), we have so far digitized and compiled around 25,000 California occurrence records from museum specimens and private collections. We have identified sites that have been well-sampled over time, with Odonata specimens from two or more time periods. Using this data, I am comparing lists of species before and after 1960 (the midpoint in our collection records) and using list-length analyses to help correct for spatial and temporal bias in collecting effort. These lists can be used to document species that have recently colonized California or have become extirpated, and those that are expanding or contracting.
Data from recent field surveys and the Odonata database will provide the occurrence locations for species distribution models of several species that have significantly expanded or contracted, including Enallagma civile, Pantala hymenaea, Tramea lacerata, Libellula luctuosa, Sympetrum pallipes, Sympetrum danae, Ophiogomphus morrisoni, Hetaerina americana, and Progomphus borealis. Species’ climatic requirements will be projected onto past landscape coverages, to determine change in distribution over time, and validated using historical occurrence records.