Meeting Abstract

P2.2  Wednesday, Jan. 5  Does immune suppression occur to free resources in the house sparrow, Passer domesticus? URBAN, A.M.*; MARTIN, L.B.; COON, C.AC.; LIEBL, A.L.; University of South Florida; University of South Florida; University of South Florida; University of South Florida amurban2@mail.usf.edu

Stressors, especially those that are chronic, are known to affect immune function, but exactly why has yet to be discerned entirely. Two hypotheses have been proposed in the scientific community to explain this phenomenon. The first attributes immune suppression to abating the autoimmune responses to self-antigens released due to the presence of a stressor. The second credits immune suppression to the freeing of resources that are more valuable for fitness than protection against infection. The second hypothesis was tested in wild house sparrows (Passer domesticus) through comparison of vertical flight test performance to antibacterial capacity of blood weekly over a six week period. Captivity was considered to be a chronic mild stressor. It was found that body mass, vertical hover, and antibacterial blood capacity decreased as time in captivity, and thus duration of exposure to a chronic stressor, increased. Immune function did not dissipate more rapidly than physical performance, suggesting that resources are not reallocated to physically demanding activities that would increase chances of survival. Further experimentation is in progress concerning corticosterone (the major avian stress hormone) levels in captive versus wild birds with the expectation that stress steroid levels will be elevated in captive birds, indicating that captivity is a chronic stressor.