Meeting Abstract

S6.5  Wednesday, Jan. 5  What is the functional significance of reduced immune function in migrating birds? OWEN, Jen C.; Michigan State University, East Lansing owenj@msu.edu

One of the many challenges birds face during migration is increased exposure to novel pathogens and parasites enroute. Migration is also an energetically demanding period in a bird’s annual cycle. When energy is limited, a bird may direct resources toward critical activities at the expense of other physiological processes, such as immune function. Increased exposure to disease-causing agents concomitant with reduced immunocompetence could make migrating birds more susceptible to disease during passage and/or make them better dispersal agents for zoonotic pathogens. Here I discuss current findings on immune function in migrating birds; how it is influenced by the bird’s body condition or migratory activity. Birds alter or suppress their immune function during the migratory period, particularly following long-distance flights and when they are in poor condition. However, the functional significance of these changes in a migrant bird’s immune system is unknown. In the second part of my talk, I will present results of experimental studies examining how migratory activity and body condition influence a bird’s response to specific pathogens, including West Nile, eastern equine encephalitis, and avian influenza virus. The hypotheses tested included: 1) migrating birds exhibit a more intense viremia than non-migrating conspecifics; and 2) birds in poor body condition exhibit both a more intense viral infection and greater susceptibility to disease than individuals do with sufficient fat stores. My results show that reduced immune function during the migratory period does not necessarily translate into an inability to respond to an invading pathogen. Furthermore, a bird’s response is pathogen-dependent and may vary depending on how and where the pathogen replicates in the avian host.