Physiological and Behavioral Effects of Ectoparasites: Does Being Bugged Cause Stress?

Western Burrowing Owls ( Athene cunicularia hypugaea ) are small, ground-dwelling owls of western North America. They often harbor fleas as a result of their prey and fossorial nesting habit. One predominant species of flea infesting burrowing owls is Pulex irritans , the “human flea”. Hematophagous fleas often cause behavioral and physiological changes in birds, such as increased preening, lower hematocrit, higher corticosterone, and higher heterophil/lymphocyte (H/L) ratios. Our objective was to examine the potential role of fleas in altering preening behavior and stress physiology in free-living burrowing owls inhabiting southern Idaho, USA. We indexed flea abundance at burrowing owl nests and recorded owl preening behavior using trail cameras placed near nests. Using trail camera data collected in 2014-2015 we calculated behavioral time budgets for owls at flea-infested and non-infested nests. With blood collected from adult and nestling Burrowing Owls in 2015, we analyzed hematocrit, corticosterone levels, and H/L ratios and examined each in relation to flea abundance. Our poster summarizes results of these experiments and discusses their implications for owl populations.