Urbanization of Dragonflies: Changes in Odonata communities over the past century

Clarence Hamilton Kennedy was an entomologist, an artist, and the first person to carry out a comprehensive census of dragonflies in the western United States. In 1914 and 1915, he travelled throughout California and Nevada, compiling lists of species that he encountered at specific sites along with notes on environmental conditions. This survey provides a valuable source of information on freshwater habitats and insects for a time when widespread urban development was beginning, and more than 50 years before there was any thought of human-caused global warming. Nearly 100 years later, I resurveyed Kennedy's original sites to document changes in dragonfly communities. In this talk, I will discuss how land use and climate are affecting dragonfly species richness, community similarity across sites, and the occupancy rates of individual species. A closer look at several specific sites will then illustrate how urbanization, agriculture and water regulation are simplifying freshwater habitats across California.

Speaker: Joanie Ball, UC Berkeley