Meeting Abstract

P2.33  Wednesday, Jan. 5  Carrying an instrument package adversely affects immune function in tree swallows VLECK., D.*; VLECK, C.; WINKLER, D.; Iowa State University, Ames; Iowa State University, Ames; Cornell University, Ithaca, NY dvleck@iastate.edu

We placed 1 g data logger backpacks on 45 tree swallows at breeding sites in Iowa and New York during 2009 and monitored returns of the backpacked birds in 2010. A 1 g load is about 5% of tree swallow body mass, near the upper end of the range usually assumed to have minimal effects on behavior and survivorship. We collected blood samples from experimental birds and matched controls in 2009 and 2010, and measured natural antibody and complement activity using a hemagglutination/hemolysis assay; bacterial killing ability; and antioxidant capacity in plasma. At least 22% of backpack birds and 41% of control birds returned. In a pilot experiment in Iowa in 2008-2009, return frequencies were 43% for backpack and 44% for control birds. In backpack birds that returned, all three measures of innate immune function declined between 2009 and 2010 and were lower than control values. In contrast, natural antibody and complement activities increased between years in control birds that returned. For control birds, but not backpack birds, individuals that returned in 2010 started with higher natural antibody and complement factor activities in 2009 than did individuals that did not return. These data suggest a moderate instrumentation load carried for a long period is a significant handicap, adversely affecting immune function and perhaps survival. They also suggest that innate immunocompetence is positively correlated with likelihood of inter-annual survival in a migratory bird.