Meeting Abstract
Exposure to urban environments can have dramatic impacts on the health and physiology of animals, however some species are still abundant and perhaps even thrive in urban environments. White ibises are good examples of this phenomenon. While they originate in and breed in remote wetland habitats, they can be found foraging in urban parks throughout Palm Beach County, FL. Further, they readily consume human food either as a result of anthropogenic feeding or from foraging in human-generated landfills. The impacts of this exposure to urban environments and anthropogenic food sources on their health, physiology, and their potential as vectors of zoonotic disease remains unknown. We hypothesized that ibises captured in urban environments would exhibit higher levels of stress (as indicated by circulating corticosterone concentrations and heterophil:lymphocyte ratios) and would show inhibited immunity (as measured by an assay of bacteriocidal activity). To test this, we captured white ibises in both natural wetland habitats and urban environments in Palm Beach County, FL. Urban sites included 5 parks, a drive-through safari, and a landfill. Immediately after capture, blood samples were collected for later assessment of circulating corticosterone concentrations and bacteriocidal ability. In addition, we collected samples in both spring and fall to examine potential seasonal differences in these parameters. Contrary to our predictions, blood collected from ibises living in urban sites showed significantly greater ability to kill E. coli compared with ibises in urban sites, and this pattern was similar among seasons. Additionally, among urban sites, bacteriocidal ability varied significantly among sites, which may reflect degree of human contact. The significance of these results and their relationship to plasma corticosterone concentrations will be discussed.
